OP, you don't specifically indicate what charges of being "a crook" you're interested in. There are two possibilities that come to mind based on Reddit traffic: first, that he profited from the work of others in his Menlo Park lab and at the Edison Electric Light Compan[ies]/other companies, and the second involving swindling Nikola Tesla. Other claims generally fall under the "too unfeeling of a businessman" or "cruelty to animals / being a dick" which, while certainly worthy of criticism, are not actually criminal in the context of the era. It's worth noting that his employees, from whom he supposedly stole so much, were incredibly loyal to him beyond the end of his own life; Henry Ford, who worked for Edison briefly, in fact created a living monument to the man.

The first claim of crookdom can be dispensed with largely on the basis of the existence of the company; Edison's company produced patents from the work of many engineers and experimenters. If this is different from other laboratory businesses, it would be interesting to hear how. The closest contender would involve Edison's construction of a trust in the Motion Picture Patents Company, which was ethically really dodgy but not actually illegal when it began.

The other one--about Tesla--is built off a failure of understanding that extends back to the 1940s, when one posthumous biographer made an attribution of a business title (a "manager" who promised Tesla $50,000 in My Inventions [1919]) to Edison. I have covered this in a great deal of detail here, in this old response. If you look at other threads, I actually pull up documents that show Tesla and Edison did not have enmity, even in the 1890s at the end of the War of the Currents; he was even laudatory of Tesla's work with X-rays. Tesla, for his part, never really assaulted Edison beyond suggesting he was unrefined and operating by brute force and trial-and-error, which he felt to be too inelegant. There is absolutely zero actual evidence that Edison was a crook in this sense.