So what are you going to do: refuse them admission? Our professional uniform covers everything from the neck down except the hands. Beyond that, any tatoos showing (face/neck) is their own mistake they'll have to live with.
I don't see it as a big deal as long as everything is clean and piercings are removed. Frankly I'm outrage at the lack of hygiene of the average cook much more than their tatoos...
Lynn Crawford is a great chef, currently the exec chef of the 4 Seasons in NY. She's done lots of television up in Canada, was on Iron Chef. She has a couple of large, odd-looking tats in the palms of her hands (ouch!). But the rest of her looks so professional, I can't imagine anyone objecting to her appearance and calling her unprofessional.