most of the time the real hot girls have heard all the best lines...your so beautiful...you have the nicest eyes...blah blah blah you get my point. after a while of catering to there every need they get bored and is partly what i think is happening here with your co-worker friend. now i do think she is a slut though!
if you see a really hot girl and you feel like tellin them how beautiful they are to see if they respond...say something like this, oh u didn't have time to do your hair tonight or what??
i swear that actually worked for me. no bull$hit! that girl told me that no one ever talked sh!t about her.