Everyone is always cool with it.
When it comes to friends:
I've told some of my friends and my brothers, nobody thinks it's weird or a big deal. They are all like "huh. Well I guess one can be attracted to that too"
One of my friends really likes watches, so I told him. Though he doesn't have a sexual thing for it himself, he responded "well, just another example of how awesome watches are"
None of my friends stopped wearing watches after I told them or anything (proof that they were not uncomfortable with it in any way. Note: I also told them I only like women's watches. Worn by women. Which is true)
When it comes to girlfriends:
Well, I've only had one.
I told her quite early that I had a thing for watches, and that she will probably get one as present some day. And she did, for x-mas.
Next time we had sex, I asked her to leave it on. (Think she had forgotten about the fetish :S, she was kind of wierd though)
After that, she never took it off before sex, but I was always afraid to give the watch too much attention, so I never got to cum on it or anything.
But yeah.
I think it's highly unlikely anyone will ever say "OMG, YOU ARE A FREAK! YOU ARE DISGUSTING!"
Because it's not. It's just a fetish we have.