I don't that the actual problem people had was Anna's sluttiness, but actually the fact that some scenes (like the one you mentioned) made absolutely no sense at all. Anna is slutty at this point. She works in a bar mainly has stripper/prostitute, she's doing porn shoots and porn cam sessions, etc. That's all fine, but the thing is some scenes of the game started to be completely out of context.
It seems slightly better now, but I still feel like plotwise this game as gone of the rails for a real long time. It's just a collection of different sex scenes appealing to different fetishes with a very poor thread connecting them