I have known several Mensa members and all of them seemed to have a screw loose.
Years ago I took their proctored IQ tests out of curiosity, then joined MENSA and attended several of their events thinking they might be interesting. I learned they could drink... a lot... and have fun, but yes, they are for the most part a bunch of misfits. I even dated a woman in that group, and eventually had to have her jailed for stalking.
I also joined Intertel, which has higher entry requirements than Mensa... but they had so few members there wasn't much going on in terms of meetings/events.
I also was a member of IEEE (only an interest required to join that)...now that was worth it. Got to visit Boeing helicopter plant in Phila., visit a high-tech trash plant being built, Conrail's control center and fun stuff like that.