I remember we had a discussion on tattoo's a while ago, and as it is not a problem even if the Sangha are allowed tattoos, whatever they be, related or not, they are not a problem.
I can see the help that 'reminder' tattoo's can give, for instance if you are getting angry, a buddha reminder on you arm for instance may aid you to calm yourself and remember the lack of importance of the situation.
I think if its a not so nice tattoo that you dislike, you would be able to lose attachment to it as you progress, if it bothers you at all that is!
"Happy, at rest, may all beings be happy at heart. Whatever beings there may be, weak or strong, without exception, long, large, middling, short, subtle, blatant, seen & unseen, near & far, born & seeking birth: May all beings be happy at heart."