His worst actual "bad" thing he did was being horrifically unprepared during the To Boldly Flee filming which made the process insufferable, but that's incompetence, not malice. There's a huge game of telephone that's happened online since the Change the Channel document dropped where Doug seems to get blamed for everything Mike Michaud does.Pretty sure Doug Walker's biggest crime is not being as funny as he thinks he is(he's still funny a decent chuck of the time tbh).
Oh, and that one time he shat on a cult-classic movie i can't remember the name of.