Daddilion it's impossible to answer. I mean, if someone asked you if you thought racists were common, what would you say? I think racists are too common, but most people aren't racist. However, people who aren't truly racist can say pretty racist things, on occasion. I think it's the same with misogyny.
A misogynist resents women. I know guys who say sexist things just because they inhabit a culture which enables that, so they don't notice or think about it, or how it actually contributes to a world which is inherently pretty hostile to women, but aren't, actually, misogynist themselves. They just reflect the culture they live in.
Honestly, I used to think very few men were misogynist. Now, I think many more were than I had any idea, because the internet's anonymity means they can express it openly with real ease and confidence. I do remember an ex had porn (playboy or penthouse letters was it?) and I looked at it and was really shocked by how the stories were so nasty about women. And it made me wonder if it was that the men who worked for the magazine had issues with women, or, more scarily, that that was what sold, so what most men thought. I still don't know the answer to that question.
I'm shielded to a large extent, because I'm married to the nicest man in the world (no, really, he is - we were friends first) and our friends are obviously good people, too. At least they are around us - I suppose one could be capable of saying stuff like that online, but I doubt it. But that's people we choose to be around.
Honestly, I don't know. I think true, women-hating misogynists are likely relatively rare, but by the same token, they aren't as rare as all that. There are too many DV cases, too many misogynist postings, too many beaten and abused prostitutes, for a tiny group to be responsible. And I think there are a lot of people who aren't misogynist themselves, as such, but who just accept the world as it is and use the language and express the ideas of misogyny. Do I think all ice hockey fans, mentioned before, are misogynists? No. I think they're just guys who don't see misogynist comments as bad.