My membership in Mensa lasted less than one year, precisely because of the climate at the meetings. After a while it became apparent to me that these were people so stuck on their self-perception of intelligence in some areas that they were blinded to their ignorance in others. They'd go around confidently expounding utter nonsense just because they didn't want to admit ignorance of a pertinent fact.

What's the line from The Englishman Who Went Up A Hill And Came Down A Mountain? "We may be twp (i.e., stupid), but we're not so twp that we don't know we're twp."

Some of these people are precisely the type who can talk for three hours about hyperspatial manifolds and Grand Unification, and then go out and put oil in their car radiators.