It probably depends on the tattoo. It might not be the best to have racist, sexist, violent and profane tattoos if you want to be a teacher.
I mean you have to think about the message if a guy has a swastica in the center of his face. A skull and bones with "n#%%ers and jews, kill them all" on his arm, a nd down the other a naked woman and something about "f&ck ing stock".
But that gets us into the tattoo police and what is ok. Most places do it on license plates though.