For the record, I was asking about generally having tattoos, not necessarily visible ones. Could be I misunderstood, or missed a post where this was covered.
On the topic of visible tattoos (hands, knuckles, neck and so on) on f. ex. doctors, I'm inclined to agree that they would not be a wise choice. Again, personally I couldn't care less if the person does their job in a professional manner, but at the same time I realize that not everyone shares my point of view.
A few years ago I was sitting in a public sauna, sweating away as one does. There were three of us guys there, and suddenly a fourth one enters. Lo and behold, it was the dentist I saw earlier in the week. A normal looking man who took really good care of my teeth, who also, it turns out, had most of his body tattooed. We struck up a conversation and he told me that he had lived in Japan for a while, and got the ink in remembrance of a friend he had there who had passed away. Looking at him at the dentist's office I would have never guessed, but it just goes to show that like people in general, tattooed folks are also very much a varied bunch.