Bigotry and myth. In Richard Current's classic Those Terrible Carpetbaggers, he examined a number of specific ones and found that they fit pretty well within the normal range of 19th c. US politicians. Some of them were simply job-seekers who had no intention of doing anything other than their jobs, and were no more corrupt than the usual American politician, and met with varying levels of success in their careers. Sometimes they went native, marrying a local woman and joining the Southern elite. But if they were reformers, intent on carrying out Reconstruction, they were eventually stymied by Southern resistance anyway.

The narrative of corrupt Northern carpetbaggers swarming into the defeated South is a part of the general Southern mythology around Reconstruction as high-handed incompetent Yankee interference. It hid the more uncomfortable truth that the often violent Southern effort to halt Reconstruction and deny basic rights to the freedmen went beyond mere corruption. The South had been a slave-owning society. It had a definite hierarchy , with noble planters on top, humble slaves on the bottom. Reconstruction threatened to upend that, mix it up. It should not be surprising therefore that politicians who were involved in doing so should be remembered as corrupt and immoral, as well as the scalawags, the Southerners who aided them. When Arkansas singer/songwriter Jimmy Driftwood began to write words to traditional fiddle tunes, in the 1950s, he summarized pretty well the scalawag image in his words for Old Joe Clark:

Old Joe Clark, he used to be

The biggest bum around

Till Andrew Johnson appointed him

The marshall of the town

He's full of wine, he's full of breeze

You ought to hear him brag

But all good rebels know that he's

A low-down scalawag.

Of course Grant would have been more accurate than Johnson, but it is certainly harder to fit "Ulysses S Grant" into the meter of a 4/4 reel.