Only think I've had this happen with a proper misanthrope (irl) on one occasion, an acquaintance, friend of a friend - self-proclaimed "Hates all men" type and very blatant about it. That one was certainly interesting.

Most often however it's simply the assumption that I can't have experience with certain things - often not said outright but it shows in small comments or body language. In these cases it is usually unintended and people don't even realize it themselves. I don't take offense, instead elaborating/clarifying. But, it has given me a lot more compassion for my fellow men.

be a better ally

I don't strive to be an "ally" or towards any other particular label. What I do strive towards, aside from the happiness of myself and my loved ones, is having a net positive impact in the world - leaving it a better place for future generations and making it a nicer place for the people living in it.