This is my own personal view, and pretty simplistic as it doesn't apply across the board but needs to be defined with each new song...

But I rather like the (probably mangled) quote from a misremembered source (Wilde? Who knows?)...

"Erotic is using a feather. Kinky is using the whole chicken."

I personally feel that this is akin to what separates a good bawdy lyric from a good just plain crude lyric. The bawdy leaves some things to the imagination, and doesn't revel and glorify the 'explicit' language, while 'crude' songs would. I'd say a good example of the poles (to me) would be The Lusty Young Smith vs. Eskimo Nell.

Though THAT would be an interesting song... "The Lusty Young Smith vs. Eskimo Nell"... Hmmmmm....

M