So in bdsm the word no and ouch aren't words to stop doing something... So when I watch bdsm porn some of he girls there are screaming and crying... So is crying really not a sign to stop.... If I was in a session and the girl started crying I would just be like oh my god and I would cry a few tears my self feeling like an ass for hurting her..... But if she is just moaning then I would keep going I think...