I hate to use such an adjective but my sister came home with a lip peircing today and she looks like a tramp. (I don't even know how she was able to get one as the peircer she went to does not give peircings if you're under 18 without Id or a parent and she's 15 and dis not provide either!)
I wouldn't say "trampy" because I haven't seen any homeless people with lip piercings, but I may be inclined to use 'un-classy', 'chavvy', 'skank-y', 'minging', and 'vile' amongst others.
I don't know if any of the above are better or worse than "trampy".
Eh. I find that a lot of people have them but it just seems weird to me. Like nose rings, sure, they can be hot. But lip piercings? They usually look weird, and sometimes junk.
I liked them a great deal in my younger life - especially snake bites - but can't say that I have much of an opinion now. Sometimes they look good and sometimes they look awful, much the same as all other cosmetic choices....