OK, here's my 2 cent's worth:
I dont' have chest hair, I have chest FUR! I get teased a lot from the female nurses, who threaten me with tape if I don't do what they say.
I never was mandated to wear a t-shirt under my scrubs, but I do anyway, as I do feel uncomfortable with all that hair hanging out, plus it looks more professional to me. It doesn't bother me in the least that someone else doesn't wear a t-shirt underneath their scrubs, and I don't think they look unprofessional, but it's just my personal feelings about myself.
Thankfully, no supervisor, co-worker or patient has told me I need to wear a t-shirt underneath my scrubs. I have been "propositioned" by patients though, which is really scary, considering I work in a
men's prison.