I personally have two piercings and 3 tattoes. Only one tattoo can be seen. (It is on my wrist). I have my nose and lip pierced, but rarely wear my nosering anymore and will probably let it close up.
I've never had any problems with people finding me unprofessional. Even in the horse world. Usually they meet me, speak with me, and find out that my appearance has nothing to do with the quality of my work. Piercings and tattooes are really not uncommon anymore. In fact, I find it a little more rare to find people without them. =D
Just my opinion though.
Also, the clear retainers DO work. If you decide to get it pierced, just take very good care of it to begin with and keep rotating the ring. I'd suggest a ring instead of a stud to begin with as the studs tend to fall out and not heal properly whereas a ring allows you to turn it frequently and will stay in no matter what.
Hope that helps.