I only have two bits of knowledge about mensa. A porn star is a mensa member, and people who are diagnosed with high IQ at a young age can develop pretty shitty traits, like perfectionism. Which sounds great, until you tell your boss you need 3x as much time as everyone else because it needs to be "perfect" instead of good enough and economically viable. Also they apparently tend to dislike not being able to grasp perfect at the first try because they are used to getting things on the first try in school. Which can result in people that may be smart, but don't actually have a lot of knowledge and know-how beyond their field of interest. e.g. Want me to calculate the square root of 23423423 in my head. Fine. But don't make me do UML diagrams.
These tidbits of info from a ex-colleague who is certifiably super smart as well as a member of mensa, but wasn't all that thrilled about it.
Personally, i've taken tests where i scored 120 earlier in my life, but on the yearly national IQ test* I score about 105-110. Mostly I lose a lot of points on the number sequences. Never had a head for numbers, and while I love patterns I just can't seem to find them quick enough in those rows of numbers.**
* We have a national IQ test broadcasted each year by one of our public tv broadcast stations. Apprently called test the nation abroad
** the number sequences like. 1, 5, 3, 7, 5, 9, ?
where you have to choose which number would be on the '?'