Should I Trust This Type of Girl?

There's some girls I've known before that have seemed really interested despite having boyfriends. Some of them will say out-loud where I can hear them that they have a boyfriend, but still want me to make a move. Should you trust girls like this? I worry that if they were to become single and get with them, they'd flirt with guys like they do to me. I've known girls like this since high-school, and even now in college they still seem to be like this.

don't trust them, but bang them if you can(without risk)