generally speaking, i like both; that said, some people wear them well and others don't.
i have a tattoo and 7 piercings (all in my ears, since putting them on my face would make waxing very painful); my boyfriend is a handsome, clean-cut guy, and i can't picture him with either. still, if he ever gets one, it won't change my opinion of him in any way.
I think it just depends. A guy with 10 piercings is probably not my thing, but one wouldn't bother me. The same with tattoos, it depends what they are and if they suit the person. If the tattoos are lame or don't mean anything to him other then he got them, I like them a lot less, then someone who is creative and the tattoos are meaningful and like well placed.