I always think of Mitchell himself in 2007's "King of Kong" in which Mitchell was viewed as the villain (perhaps unfairly at the time) but he didn't do himself any favors in making himself seem like a sympathetic character.
The suspicion was perhaps heightened by the fact most people thought he was a jerk and wanted to see him taken down, except for his groupies who worshiped him.
At this point, it is fairly conclusive that he has cheated in several instances.
I don't think so. The film had footage of Steve Wiebe telling his kid he couldn't help with the potty because he was busy gaming.
> "And again, [Mitchell is] not in it much, but when he's in it, he provides enough evidence that the stuff in King Of Kong was not all that fabricated when it comes to his attitude." (35:48.960 --> 35:59.600)
[1] https://soundcloud.com/jimquisition/the-spin-off-doctors-cha...
Not to mention that he cheated and was the villain in reality.