What exactly would be immoral about dancing for money anyway?
It is entertainment, and both the dancer and the "client" are participating of thier own free-will. We pay for all other forms of entertainment - paying for entrance to a club, tickets to a show, concert or movie, we pay for games, we pay for cable TV, and we pay for the internet. What is so different about giving money to someone who wants to entertain you by taking off thier clothes to music?
It is exploitative, but not in the way most people think. Think about it - these women are doing a very simple thing, taking off thier clothes, and shaking thier respective body parts. And, one person can give hundreds of dollars to watch this for an hour. You could just as well download some videos off the internet for a fraction of the price. But the girls keep shaking and the men keep giving. If you've ever seen some of these girls work, they can get men to pay for lap dances for hours just by being flirty. So, who's really being exploited?
Is it immoral because it encourages infidelity, or an obsession with sex? Well, such behaviors are the responsibility of the person. It's not the stripper's fault that a man cheats on his wife, just like it isn't my teachers fauly that I fail a test if I haven't studied. You have a personal responsibility to control your own behavior.
Is it immoral because it's percieved as lewd? Well, that's a personal opinion and has little to do with ethics and morality.