There are lots of reasons it doesn't go well. I've had a lot of lesbian friends over the years because I'm fairly gender non-conforming, but I'm not gay. But they routinely assume I'm gay or bi. It's not that I'm insulted by being LGBTQ+ -- heck, I wish I were! -- it's that I'm insulted that they think they have a better handle on something as intimate as sexuality than I do, especially when there is obviously a spectrum of "gayness" (for lack of a better term). In the end, it's better for people to figure themselves out and better to wait until asked rather than give an opinion that labels and pigeonhole someone. Heck, I know people who are offended by astrology and the MBPI for the same reason -- they can't stand being "summed up."