To be fair to the OP, he's asked a genuine question and doesn't deserve knocking for wanting a tattoo. I don't have any but my OH does and it's quite nice actually. Just not visible under most circumstances. The bottom line is that it's the employers choice about how their staff look, dress and how they present the company to their customers... and that can, and should IMNSHO, include visible tattoos. And the higher the bar, the more high-profile the job then the higher those standards will be.
Years ago we did an interview with a potential employee. We were incredibly relaxed in our dress code (when customer-facing the normal get-up was clean jeans, trainers and the obligatory aircraft t-shirt). But when faced by a foul-mouthed person with unwashed, rancid looking, multi-coloured hair, facial piercings and visible tattoos, our instinctive reaction was "No, we don't want this person anywhere near our customers because those customers will run a mile". So we didn't employ her. Brutal, maybe. Simple, yes.
Just my 2p worth
CS