Since the typicial guys in the manosphere were at some point abysmal with women it wouldn't come as a shock that their knowledge about sex comes mostly from porn. Roosh made a post on his blog about whether American women had looser pussies. Keep this in mind for some of the points I'm going to raise below.
In an earlier post, "Going Abroad Just to Bang 6s? -- Taking down Roosh V", I pointed out that Roosh only goes after girls who are DTF (which is why there is basically no mention of girls he has slept with using "day game"). In a nutshell, Roosh only hooked up with American girls who were openly DTF the same night and based on THOSE GIRLS makes generalizations of American girls as a WHOLE. If you're still not convinced, read Roosh V's blog post "The morality of game".
He writes:
I know they love fucking, partying, drinking, and playing the game. They feel proud to be successfully emulating their horse-faced television role models, and are as likely to pump and dump me as the other way around...
...and:
After I was done with a girl, I knew it wouldn’t take more than a couple weeks of going out for her to get boned by a new man...
Does this sound like the type of girl you bang? It doesn't to me. But then I already mentioned the girls Roosh goes after. However, Roosh clarifies this for us even further...:
I’ll be the first to admit that many of my bangs back in the States were HATE FUCKS. The masculine attitude and lack of care these women put into their style or hair irritated me, so I made it a point to fuck them and never call again.