How to tag a Piercing Parlour?

The general rule of thumb is to use shop=beauty for anything which is concerned with any kind of personal adornment which is not either a hairdresser or tattooist. You can then use the widely used beauty key to provide the extra detail.

I was introduced to this concept long ago at a London mapping party, and it works well, at least in part, because many parlours offer multiple services or are rather specialised. This approach is very widely accepted, for instance there are less than a hundred shop=nail_salon compared with over 11,000 shop=beauty + beauty=nails.

PS. I don't know why tattoo parlours didn't come under this rubric, but they don't.