So bellydance is stereotyped by everyone as an expression of sexuality and availability. This could be a topic for a whole new thread ("How much is belly dance perceived as expressing the body, rather than expressing the music, and how does this cause the visual to subsume the audial and lead to stereotypes about a dancer's 'message' to the audience?")
But as you are so eager to affirm, not all belly dancing women are prostitutes, even if your 'misogynist troll' had only met ones who are. Equally I would be eager to affirm that not all male belly dancers are gay, despite your own experience of only having met gay ones. We all carry sexual stereotypes in some measure or another. We think our own stereotypes are the 'norm' (bellydance in empowering) until we encounter someone else's (bellydance is degrading). They reflect the social expectations and perceptions of the culture we grew up or live in.