I've almost exclusively heard the term applied to women.
When applied to people, "tramp" is always a loaded, sexist word. Applied to men it means they are poor and itinerant, being roughly the equivalent of "hobo" or "swaggie". Applied to women, it means they are sexually promiscuous. One relates to a socio-economic status that might not be the tramp's fault (and is frequently mythologised positively in art, literature, songs etc.), the other implies that the woman is of bad character from choice.
I'm totally not a body-art person, but I'm familiar with the term "tramp stamp". Is there any term for tattoos on men that has the same currency in general use? I can't think of one, and that immediately makes me suspicious that the term is a sexist insult in addition to any disrespect it shows to people with ink. I don't have much to say in here, because it is not my thing, and I prefer to lurk and learn, but I don't understand why someone would post in a forum thread
specifically dedicated to tattoos and other body mods, using negative vocabulary towards tattoos, or the people who get them.