I grew up in one. It wasn't horrible in my case, they mostly just said it and moved on, but I've seen the worse ones and they are pretty bad.

Here's a typical example. Nearly every single post by this person is about demeaning men and saying our only purpose is to support women who are goddesses and slave to society. Otherwise we are worthless, but women are worth more than any man no matter what they do. One of the posts even blamed all of society's problems on men who have lives of their own. The only difference between traditionalist versions and feminazi rhetoric is that the former stresses women "submitting" to men...and guess who usually has a kink for submitting to men. So even that is their win overall.