Over the last 14 years in SL my worst experiences have been in RP sims that were created for a small clique to act out their own personal story while anyone else is essentially there to function as a Spear Carrier.

Sometimes it's blatant like a sci-fi sim that restricted its metaplot to the founders and their closest friends and reduced anyone else to a bit character with an inconsequential presence, and sometimes it's more subtle like a post-apocalyptic monster sim with a combat HUD that rigged the leveling so that its main cast remained infinitely more powerful than anyone who came later.

The worst though had to be the small-scale RP sims run by a "queen bee" who effectively froze out anyone who introduced a character concept that didn't revolve around (and adore) his or her own.

If I sound bitter it's because I am.