For a long time I was on a RWBY RP site that could have been great if not for the rampant and *not allowed* sexuality and borderline pedophilia that went on both in character and in the IRC chat. However, I did meet a long-time friend on that website, so something good came out of it. 

There's also the classic stories of GMing when a writer comes along who just won't. accept. our refusal. Buddy would NOT accept that his superpower (literally to edit ATOMS in ANYTHING, nothing OP here eh) was OP as shit. Turned into a huge pissing contest despite our sincere efforts to remain civil. Gotta love when people turn to personal attacks in argument.