My dog Ted comes to work with me, but is confined to the staff room. We are a hair salon as well as beauty, and he is most definately not allowed near the beauty rooms. I worry more about what he could catch in the hair salon(he eats hair!) than what clients are gonna catch from him.
He is an ultra cute cavalier king charles spaniel by the way, and I think, more popular than me! We do not serve food in the salon, so there are no laws saying he can't be there.
In four and a half years, I have had one client complain. We have had countless clients turn up with dog toys, treats and chocolate drops for him however. One of our clients always insists on taking him for a little walk after his haircut, as he enjoys dogs but can't have one himself.
All in all, Ted being there does no harm, and is better for him than being left at home all day with those pesky persians (who are a bit mean to him)