I'm unqualified to answer that, and to be honest I don't really care one way or the other. It's just one of a thousand reasons to wish he'd never held office. But since he's blocked his tax returns from being investigated by anyone for four years, lied about why, and fought at every level of the US legal system, I would be amazed if they are squeaky clean. Even if it shows that he's merely a con man, rather than a criminal, it would still be interesting -- the man has built his reputation on having a fine business record, but that's almost certainly a con (if not legally then morally, at least), built on mountains of debt and on inheritance from his father. The biggest blow to Trump, I expect, would be the revelation that he's actually a failure, and therefore will go down in history as the textbook example of a man who fails ever further upwards.