Most recent:
Staff on a super-hero game engaged in behavior that deeply violated player's privacy and then proceeded to organize what I can only describe as an "arranged stoning" of that player in front of people they had communicated with when handing down the decision to expel them from their game. During this, uh, hearing, they refused to provide any concrete examples of genuine malefactor behavior, at least, from the player being banned. This has been talked over extensively in other threads.
More recently on a WoD game, I chose to leave because I realized I had an incompatible temperament with the person running the vampire genre. Some people were (and are) fine with them -- I viewed them as witheringly mean, trying to take a "stern manager" approach and coming off more as "Horrible Boss", trying to use something I wanted to do to steer me toward PvP in ways I wasn't comfortable with (said staffer has, based on my observations, developed a rep for going after people's +sheets without talking to them, and engaging in excessively punitive response without adequate communication as a storyteller, among other things), etc. In the end, I realized my experiences with that person made me dislike and mistrust them tremendously, there was no "corrective action" that could fix that, and that the best solution was for me to say my goodbyes and quit logging in.