It tends to be nice tits, or ass, or pussy, or pretty faces that does it for me on a prossie... Tattoos, well I can take them or leave them really. I think a girl can either look really nice with them if done well, or it can be very off putting. But I'd always tend to think she'd just look better without them.
Piercings, I have similar thoughts on... though I'm not terribly keen on having the taste of cold metal in my mouth whilst trying to enjoy oral or kissing. Don't mind ones on eyebrows or ears or nose or belly buttons or whatever, but prefer not to see ones around mouth or genitals. Like tattoos though, if I fancied the girl and wanted to fuck her, it wouldn't stop me, and it some cases I think it can look really nice, but would tend to think she'd look better without them.
All that being said though, I don't think I've actually met a prossie who doesn't have something like that going on to varying degrees. Something I've just come to expect to see. To me, in some ways, it's more unique and interesting to meet one that doesn't have tattoos.