I knew I wasn't the only one annoyed by those, I had gotten numerous FC invites but rejected them for the same reason for awhile, I joined the one I'm in now because the FC leader actually took time to talk do some stuff together and then invite me once he actually knew that we would get along and that I actually speak english. Most if not all of the members since are cool to talk to, even if the FC is rather small (Quality over Quantity ).
Small anecdote to show the opposite, some Japanese FC (or at least I think they were japanese) sent me an invite once and I tried to talk to the person inviting me but all I got in return was a bunch of Japanese. :/