A good club song for me is something that can get the job done of making me want to dance, but without feeling stupid doing so. If I get out there and hear a Full Metal Jacket quote taken out of context and repeated "skull fuck you skull fuck you skull fuck you..." I feel like myself and everyone around me is kind of a hackneyed douchebag for getting down to it. It's juvenile. On the other hand, I still haven't found a good way of dancing to the full-length version of "Bela Lugosi's Dead".
For me, it comes down to MELODY. I need melody just as much as I need rhythm. And also, as I've said, lyrics that don't make me feel like I'm a hairy-necked jerk that collects swords.