I haven't encountered that, but I have been prejudged as "materialistic" and having no deeper meaning for existence based solely on the fact I'm an atheist and not for any other reason. As an aside, I was once in the military (years and years ago) and many of the males assumed I was a "loose" woman with no standards because there was an assumption that all women in the military were promiscuous. I'm not sure why that was, but it was definitely the experience I encountered. Anyway, perhaps younger, single, atheist women might have come across the assumption that they're promiscuous?
I have not run across it, but I was older and married when I finally admitted I was an atheist.
On a related issue, one thing I have found is that many of the people who are judging others' sexual morality from their own "Christian" viewpoints are often the ones later discovered to be having affairs with multiple people while they are married. They will come up with all sorts of excuses, but the fact is that they are violating their own promises to their spouse.
One of the "best" examples of such a good Christian was a lady who had her much-older husband in a nursing home. She was drunk, and saying how I make her "so mad" because I don't believe in her delusions, all the while she was making passes at my husband. Golly gee! I'm glad she told me she was a Christian, because I sure couldn't tell from any part of that!
I think your analysis is about right on.
I also notice a good deal of hypocrisy in the whole morality of theists. It seems that if you look too hard at any of the ones who puff out their chests about their "Christian morals" and talking of the "immorality" of everyone else - society, atheists, feminists, gays, a particular ethic group, or anyone else, that I'll often find that they are engaging in sexual behaviors that violate their own morals, or are unsafe or downright exploitative of their partners - often in violation of an outright promise of some type and their own religious teachings. The probability of this is proportional to how much they rail about it.
This goes from anyone from the Ted Haggards to the Catholic priest scandals.
As much as I abhor the actions of Westboro Baptist Church, the things they do really are in accord with the book they say they believe in. It's the "moderate" Christians who give their approval to these actions, by holding the Bible up as the ideal. I have not heard of any sexual misbehavior by the Westboro people. The Westboro Baptist Church shun former members, including of their family members, who do not or no longer accept their Church's teachings, and Fred Phelps' teachings. The Bible says to "shun" the apostate, not to "love" him and bring him back into the "fold" so he can repent.
It's too much to hope for, but the moderate Christians should be able to see that these Westboro wackos are doing what they say should be done.... and it's ugly.
I never did encounter that when I was younger (not now in middle-age either.) My daughter hasn't either. I know a hell of a lot more religious people who have had sex not according to the 'rules' of their religion. I obviously don't think anyone's sex-life is anyone's business, but a lot of religious people claim to follow what their religion dictates, and obviously don't.
I've experienced that, yeah. It's not often, but it happens, and I think maybe it happens more on the internet or when people speaking to me in person aren't yet aware that I'm one of those atheists they're railing against. Other young atheist women definitely get it worse than me due to the intersection of their (lack of) faith and race. I get the feeling that a lot of religious people let me slide under their whore-radar because of preconceived notions that Asians are sexually modest. It would probably be a different story if I were a black or latina atheist.
The only time someone seriously said that to my face was with a crazy campus preacher who was trying to make some point about being a "loose woman" if you wear t-shirts and jeans, and he singled me out specifically with his Angry Pointer Finger of Doom. (He said he supported ankle-length skirts. When he came back the next year with a female sidekick, she was wearing jeans and he dropped that bit from his routine. *ahem*) He was craaaaazy, because really, if you're going to rant about college girls showing too much skin, it'd only be logical to point out the one in the midriff-baring halter top instead of the one in baggy t-shirt and jeans. My reply was, "Wow. I must be the loosest virgin ever." It was hilarious.
...Now that I think about it, though, I regret not being witty enough to also slip in a comment about equating the loose-ness of one's shirt to the loose-ness of one's morality. Or maybe I should have made a joke about how he chose the college preaching gig in order to perv on women young enough to be his daughters and he was angry at me for showing the least amount of cleavage that day. He did have a tendency to bring up how many sexual conquests he had before he "found Jesus"...