I get it, too. I hate blind invites. It's one of the rudest things in the game, IMO. I always turn it down. What really bugs me is when the same person keeps inviting you. It's almost as bad as RMT shouting.

When I join a FC it will be because someone actually took the time to talk to me and make friends first, not because they spammed me with blind invites. I'm more likely to blist you than join you if you keep that up.