I'm a groomer at Petco, and their floors are cleaned every sunday morning, so I'd say sunday's and mondays would be probably your safest bet. I don't believe the carts are sanitised though, so if you're going to take your pup through these places to socalize him ask them what days they do their floors. We normally tell owners not to bring them even to be groomed until after their.. second set of shots I think?
As concerned as I am about things such as parvo and distemper, I know my dogs are all fully vaccinated and protected from those viruses - I just heard yesterday (from a friend at work) that vets are cautioning people from frequenting places where many pets visit because of the dog flu that's been going around. From what I've heard, it's not deadly like parvo or distemper, but it can make your dog sick if it picks up the germ.
We've taken Lucy and Meau to PetSmart a few times. Lucy used to be slightly frightened of the vehicle itself - once she was in a car and on the road she was fine, but coming up to the car, she'd pull back on the leash with a wild look in her eye... since we've been going fun places like PetSmart or Diamond W Animal Essentials (a locally owned pet place), she's been looking forward to car rides and hops right in to go!!
Now that I've been "warned" to stay away from places like PetSmart, I'll have to find other fun places to go so she stays happy with car rides - being it's a brutal winter here in the north country, there aren't a lot of places that come to mind... Any suggestions?