Hanging out with a jerk in Wailing Caverns? See if they have a level 60 you should avoid like the plague as well. Convinced your guild banker is selling your precious loot for profit? Catch the level 5 alt selling on the auction house and see if you can trace it back to the evil banker.
Do I like the idea? No. I think it would lead to some short-term chaos, invasion of privacy and it would destroy my alt vacation on the same server as my main. Yes, I could just create my alts on another server, but I like to outfit my alts in bags and some decent green armor. But it certainly would be interesting if all our secret alts got "outed".
What do you guys think? Would you like a peak at everyone's roster of alts? Or could you really care less?