I have heard that line many times, and most times it is just a line, but I have had a few times where the dancer got very wet, and all but two of those time involved some stimulating of her on my part in a full contact club.
The first time occured during a two for one, feature act, two for one combo. Midway through the second song of feature act, she said she really didn't want have to go back to the dressing room and would give me two free songs if that was all right, and she added "plus I am really horny". Who was I to argue, although I doubted the horny part, except during the first song of the second two for one she said into my ear, "oh my god I am about to cum," and proceeded to grind my crotch for about thirty seconds then paused a bit. She spent the rest of the two for one basically hugging me. I only got one more dance from her after that, then she seemed to avoid me.
The second time was one of my favorite, back when the club used to give $10 dances. I got 4 songs from het that time, and was about to leave. She said, "you don't quit now when you got me all hot and bothered." I told her I was out of funds, and she countered that the rest of the songs were free. She often gave me one or two free dances if the club was dead, or when she was avoiding bachelor's parties. So I thought nothing of it. This time she continued for four more songs, then like other dancer told me, "I am cumming," and got my pants pretty wet. She stayed at the club three more years before retiring, but never repeated that experience, although she still give me a free song or two.