What do fellow rationalists think about Mensa?

It’s not a typical OB/​LW subject, but Robin correctly pointed out that most rationalists are outside OB/​LW, and so I’m asking about one of the organizations that might hold many of them.

A couple of weeks ago I took a supervised IQ test by Mensa due to curiosity and for some CV padding (cheap signaling is a perfectly rational thing to do). Now I got a letter back from them that I’m in top whatever %, and they’d like me to join. I wasn’t really planning joining Mensa, or anything else, so I’m wondering—does any of fellow rationalists have any experience with them? Is it worth bothering?

As a bonus here’s a quick description of their supervised IQ testing process:

  • First you get Catell scale B test, which is a mix of English word puzzles, picture puzzles, and logic puzzles. It obviously discriminates against non-native speakers. It has somewhat tight per-page timing. It seems to have stddev 24.

  • Then after a break you get Catell Culture Fair test, which is pure pictures, on extremely tight and stressful per-page timing. It seems to have stddev 16.

They compute percentile based on both tests separately, and higher of two counts as the result. So you can has 0 points on one (if at all possible), and respectively 148 /​ 132 on the other, and you’re in (2 stddev above mean, or top 2%). The tests obviously check knowledge of obscure English words and meanings and ability to deal with pressure in addition to intelligence as such. Well, I guess no test is perfect.

So Mensa—good or bad?