I use Petco for grooming, but with that said the reason I use Petco is because I prefer the groomer who works there. Paula (the groomer) came recommended by my neighbor after I had a really bad experience with PetSmart.
SophieKate came back from PetSmart looking like she was never cut and her toenails were not trimmed at all. PetSmart also schedule her grooming for the next 18 weeks (once every six weeks) which I thought was kind of pushy since I told them when I picked her up that I thought they forgot to trim her.
Grooming has been on of the topics I have followed very closely on YorkieTalk since I saw some discussions where the poor dog had been cut by mistake (or by a careless groomer).
I really like my groomer now Paula, she always makes a point to come out and greet me and we discuss exactly what I want done with SophieKate. In fact SophieKate is going there tomorrow for a bath and she needs her visor trimmed and her little butt fur/hair cut.
Like the others have suggested, get recommendations, observe the groomer if you can and I would also always talk to the person who is grooming before leaving my dog.
__________________ Cheryl,Mom to  SophieKate |