How come porn always gets a bad rap, it is a valid art form enjoyed by sad lonely pol such as myself.. anyway... erotica...
It is as SHaron and Jamie pointed out subjective.
Some people find leather or lace erotic, though it is not the fabric itself that is erotic, it's the thought of the person in them.
Nudity in itself is not erotic, having done life drawing for 5 yrs in college I know its not. Erotica is in what is suggested, sometimes less is more.
I believe erotica is to do with a number of factors...
maybe enviroment, clothes, the vital stats of a person, their attitude, the amount of alcohol comsumed before you have these thoughts lol.
El riesgo vive siempre!