I try not to have pet hates, because that way madness lies, or at least a very crabby old age. But one thing I really dislike is when people say “Your mileage may vary”.
Whut? After I’d seen YMMV a couple of times I looked it up and found out what it stands for, but that doesn’t begin to explain what it means. My mileage? Who’s talking about cars ffs? And even if we were talking about cars, of course my mileage is going to be different from yours. You have a different life from me, almost certainly living a different distance from work, shops and schools than I do. It would be more remarkable if my mileage were NOT to vary from yours.
OK, I admit, I do have a fairly unreasoning hatred of phrases which simply make no sense in the situation people are applying them to. (It may be relevant to note here that my ASD son tells me I take things too literally.)
Anyway. The phrase, if I’ve understood correctly in trying to work it out from context, seems sometimes to be used to convey the meaning “You may choose to disagree”. In which case, I have to wonder why they’re wittering metaphorically about cars when they could simply say “that’s just my opinion, of course”, or if we’re being cool and internetty about things, “imo”.
However, more commonly - and this is the second reason I hate the phrase - YMMV gets used as a conversation stopper. People use it to mean, “Here’s what I think, and I simply don’t want to hear what you think. Don’t bother answering. This conversation ends here.” And however cool they think they're being, that's just rude.