Dude, I know a couple of ex-special forces soldiers who are not just smarter than me, but could kill me in ten different ways before I could blink. They got inked.
In fact, Chinook, don't a lot of you military guys get tatoos to identify what unit you are with?
Me? They're not my cup of tea. But to each his own. Now, are there career repercussions to having a tatoo that's visible? Yes, there are. But the intelligence of those who get tatoos goes all the way from just barely able to write their own name to geniuses who speak three different languages fluently and who are studying for their PhDs.