I joined two world guilds, Mages' and Fighters'.
Both of these send you on quests that are bugged right at the end or extremely difficult. In one case, the quest bugs out with a portal into 'wherever' that won't close. In the other, you have to fight a boss that's well OP for a solo player.
It's bad enough to have to abandon both of these quests after spending forever getting to the end and losing out on all the XP you really deserve to get. But here's the thing, the damn NPCs keep running up to me wherever I am and trying to give me the quest again. They are becoming a serious pest. First couple of times I thought it was a new quest and didn't realise until I got to the location.
I'd quit the guilds but I've already invested skill points and have some exp invested now. Anyway, be warned.
'Clever' sigs get old real fast - just like this one.