This is a really good question! We discussed this very topic in my Reconstruction class this past semester. The Redeemer (conservative white democrat) movements in the south sought to take legitimacy away from the Reconstruction governments in a number of ways. One of those was accusing them of enormous corruption. They generally did this after the fact by launching "investigations" into the Reconstruction governments. While some of these reconstruction officials were corrupt, so too were the conservative Redeemer politicians that came after them. Similar accusations that Redeemers used against Radical governments were later used by more populist leaders against Redeemer politicians. A notable example that we discussed was Ben Tillman (a "populist") in South Carolina. He accused the Wade Hampton government(Hampton had been one of the richest and most powerful men in the state) of gross corruption.

American politics at this time were very corrupt in general. Politicians had no qualms about taking kickbacks from railroad companies and other industries. The Grant administration itself was rocked by multiple scandals. I can look up some more specific numbers and quotes from Eric Foner A Short History of Reconstruction and C. Vann Woodward Origins of the New South if I'm able to swing by my office tomorrow.

Also it's not like the conservative governments that ran the states exactly had the best interests of the average citizen in mind; South Carolina basically had it set up to where the planter aristocrats completely dominated state politics and ran things for their own interests.

Richard Nelson Current wrote a good book on this question titled "Those Terrible Carpetbaggers". He took several different ones- some well-connected and important, some minor. Sometimes they fought for Reconstruction, sometimes they became more Southern than their Southern neighbors. The book's a bit old, now, and likely some broader surveys have been done, with more examples, but I don't think there's been a great change to his general conclusion that, while there was certainly a lot of native Southern hostility to them, the carpet-baggers were no more corrupt than the average late-19th century politician, and were sometimes better. An example of the better ones is Albion Tourgée

The answer is a convoluted yes and no. First, we must dispel the notion that Reconstructed southern state governments were dominated by African Americans. Second, it is important to understand the motivations and roles that northern and southern Republicans played in these governments. Then, we will discuss the positive and negative aspects of these governments. Lastly, we will highlight how Reconstruction was mischaracterized in subsequent histories and legends.

According to Dr. Powell and Dr. Nieman, African Americans did not form a majority of local, state, or national politicians in Reconstructed southern states. Rather, it was white northerners who dominated positions, with a number of white southern unionists, and some African Americans. "Negro Rule" as it was coined by southern Redeemers, sought anyway possible to discredit the regimes of Republicans during Reconstruction.

Why did northern Republicans become a dominant political group in the South? They did not begin this way. Most were entrepreneurs who came South to invest in vacated plantations or railroad speculation, others were old soldiers who tried their hands in business or felt an affinity for the area, and lastly, outright exploitative businessmen. Many of the entrepreneurs and soldiers who sought to make it in the cotton game lost their investments when the Cotton Market crashed from 1866-1870. Cotton prices declined precipitously, wiping out much of the capital northerners brought with them. Furthermore, railroads are a costly venture, and simply not enough venture capitalists came to the South to invest in them. This left a large group of northerners in the South without a livelihood, leading them to enter politics for income and prestige. Not all of them had jaded motives, many genuinely believed in helping the South. But with all things, making ends meet came first, and politics was one of the best ways to do it. Networks of shady businessmen existed from the war well into Reconstruction, enabling less-than-moral politicians to reap additional profits. However, it is important to look at local basis for this, since it varied from state to state and election year to year. African Americans received far fewer political favors and appointments than their influential voting bloc warranted. Pointed pressure from black politicians could force concessions from northern Republicans in the South, but this happened far less frequently than southern Republicans who had been unionists during the war and most likely Whigs before it. Southern Republicans had an obvious stake in all this, strip the aristocratic planters of their prewar power to ensure the dominance of upcountry, poor, and unionist white southern Republicans. These groups, however, became disenchanted, as I will describe below.

According to Dr. Thorton, southern Reconstruction governments placed additional taxes and fees on all southerners as a way to pay for the expanded social services. Thorton points out that many of these services went far beyond what these southerners typically expected and many viewed it simply as efforts at "black upliftment." Take home pay in this era very rarely occurred in specie (legal tender) and often took the form of bartering crops for goods and services. Many of the new fees reduced the ability for southerners to accumulate specie, leading to increased disenchantment. Was it corrupt? Depends. Schools, hospitals, roads, railroads, and other services expanded and were certainly utilized. Thorton argues that whites did not see an expansion of services that would be on par with the additional fees accumulated, citing prewar private schools as an example. The problem with this is the conflation of individual, limited private schools with a public school system. In the antebellum era, children brought their own books and supplies to these private schools, usually near urban areas, and certainly limited to the upper middle and middle class. Much of education was home schooled in the rural South, so the expansion of education was certainly a benefit to all. Except for the fact that white southerners often prevented their children from attending schools with black pupils. Combine this increased fees with the extreme deficit spending of numerous southern states, the busting of state bonds, the failure of railroad investment, banking crises, and the cotton market crash, all led to increased financial distress in the South. All this played into Redeemer electoral efforts.

So was the Reconstruction governments corrupt? Some certainly were, railroad companies received questionable financial backing, slush funds went to Republican politicians, more than one such politician directly stole state funds and funneled them into private accounts, and speculators took advantage of connections to receive the best lands. However, as described above, legitimate progress was made in expanding social services, for a time in certain places, racial equality was briefly raised, African Americans received the benefits of due process, representation, and legal and economic benefits than previously experienced. Despite the failure to build up railroads as had been accomplished in the North or burgeoning West, major progress was made and southern railroads did expand its services. All of this, of course, was made at great cost, both corrupt and legitimate, in an area not as accustomed to direct local and state investment as had occured in the antebellum era (this is actually important, the actual southern expectations of what government provides was certainly different than from what other northern citizens did).

Redeemers funneled discontent, fraud, and outright violence into an electoral strategy that won the southern states back, one by one. In some places like South Carolina that had counties of high black demographic ratios, the charges of "Negro Rule," rang more true that in Upcountry Arkansas or Alabama. In these latter areas, the charges of corruption appealed more to poor whites. But this was not a stark line in the dirt. Through a process of disfranchisement, electoral competition was reduced, which allowed increased power among black-belt counties were the minority white Conservative Bourbon Democrats. Only many years of conjoling, abuse, violence, fraud, and constitutional or statute manipulation could overcome competition that allowed Populists, Progressives, and the remnants of the Republican Party in the South to pose a challenge to Single Party Democrat rule, the turn from Redemption to Restoration, as Dr. Perman argues. Even up to the late 1880s and 90s, these challenges remained. The Democrats continued to cite the "failures" of carpetbagger, scalawag, and Negro Rule governments, making their way into the histories of the works of the Dunning School, best represented by historian Charles A. Dunning. These histories enshrined the myth of failed Negro Reconstruction, which remained a dominant interpretation of Reconstruction for decades until the likes of W.E.B Du Bois (well before his time), C. Vann Woodward and others challenged it.

Sources: Lawrence Powell, “The Politics of Livelihood: Carpetbaggers in the Deep South,” in J. Morgan Kousser and James McPherson, eds., Region, Race, and Reconstruction: Essays in Honor of C. Vann Woodward (1982); J. Mills Thornton, “Fiscal Policy and the Failure of Radical Reconstruction in the Lower South” in Kousser and McPherson, Region, Race, and Reconstruction; Donald Nieman, “Black Political Power and Criminal Justice: Washington County Texas, 1868-1884,” Journal of Southern History 55 (1989): 391-420; Eric Foner, Free Soil, Free Labor, Free Men: The Ideology of the Republican Party before the Civil War (1970); Mark Summers, Railroads, Reconstruction, and the Gospel of Prosperity: Aid under the Radical Republicans, 1865-1877 (1984); W. E. B. DuBois, Black Reconstruction in America 1860-1880 (1935); William A. Dunning, Reconstruction, Political and Economic (1907).