LAS VEGAS -- Here in Sin City, a modern Gomorrah built on the notion that there's a little bit of naughtiness in all of us, erotic dancing is hardly excessive in a town that takes $10,000 blackjack wagers. One type in particular, the lap dance, in which scantily clad women bump and grind on male customers in a sexually suggestive way, has been for years a staple in the ''gentlemen's clubs'' that prosper away from the glare of the Strip's mega-resorts and casinos.Erotic entertainment is so much a part of the landscape that even people outside the industry were scratching...