It wouldn't make much sense for someone to put down their IQ on job applications (for most professions at least). The IQ test is mostly made up of logical, pattern-based questions, so if anything, it can be construed as a measure of how well someone can analyze patterns.
But IQ tests aren't that useful for judging someone's qualifications for a job. When I took the DLAB to judge my qualifications for language study, I scored fairly high, and as a result was assigned a particularly difficult language. But still, I knew plenty of people who took it and got lower scores but were still assigned difficult languages, and ended up doing better than the people with better scores.
Local Mensa representatives here would like to make people think that that is true. It would certainly help if 90% of their membership here wasnt filled with hipster gits who lack anything better to do, and whose parents have constantly dumped boatloads of cash their way.
Being a part of Mensa is a good way to open doors for someone, but there's still that group of pretentious assholes who do it just to hold it over everyone else's head.
But every job, every group has people like that.