I've actually had very little problems on the mentor chat on my server, but then most of the people in the mentor chat were people I already knew and the majority of them are good people. The real issue we had is somehow RMT bots were being invited (easy to spot, random character names in Central Than as level 7 THMs) and needed to be kicked but it was all mostly smooth, though we couldn't really identify the people who were inviting the bots so we could remove them from the channel as well.