I'm going to regret this, but here goes.  I am trans, and a card carrying member of Mensa.  I have no need to convince you of that.  I am horrified at the vitriol being cast against a fairly innocuous group, by people who obviously know nothing about it.  
     From the Mensa website, "provides a forum for intellectual exchange among members. Its activities include the exchange of ideas by lectures, discussions, journals, special-interest groups, and local, regional, national, and international gatherings; the investigations of members' opinions and attitudes; and assistance to researchers, inside and outside Mensa, in projects dealing with intelligence or Mensa."
I admit to being a nerd with some pretty esoteric interests.  At parties I put people to sleep because I often use complete sentences and even paragraphs to put across my ideas.  Even my wife occasionally starts snoring or gets "the dazed" look.  I don't get that around Mensans, and don't we all tend to enjoy at least a little time around people like ourselves?  Nothing wrong there. 
     I agree that being in Mensa means nothing more than having achieved a high score on a test.  A test of one very important form of intelligence in a world where there are a number of kinds of intelligence.  It can be shown, however, that intelligence does equate with approximately $500. per year of income for every 1 IQ point over the average.  I think it shows that that form of intelligence does have some worth in our society. 
      At the 50th anniversary of Mensa, held at Disney World here in Florida, I met an older transitioner who taught advanced calculus at UC Berkley.  She was head of a design team that perfects "quietness" in nuclear submarine profiles when underwater.  Mensa gave her an outlet to tell her story in a lecture at that worldwide meeting(for those who wanted to attend) as well as a featured story in our national monthly magazine.  Maybe that is why I felt a need to respond.  I don't normally mention that I am a member to anybody.  I just think that they have been open and accepting and maybe deserved a little bit of defending.  Sorry for the rant.