I did the PetSmart thing for 7 months. I was hired as a trainer but was only able to schedule 1 class per week since I was apparently only a "part time trainer" as opposed to a "full time trainer." I got a few privates in there which was nice, but yeah. It was SO MUCH other retail stuff. Which I don't mind terribly, but only getting to be scheduled 6am-noon every other day meant I got to stock shelves an awful lot and check for expired food. Not so much training. And it was therefore difficult to sell classes because NO ONE WAS there. Ever.
I probably would have enjoyed it more if they were honest about the hours they were going to hold me to. I did, however, get to add to the curriculum and teach things more or less my way (using mainly R+ obviously).
I did the kennel/boarding environment thing while I was in TX and got to do one on one play times with dogs, and that was really fun. I didn't even mind so much the cleaning of poop and kennels because the place was really well-run and the people who worked there were great and passionate about the dogs/cats in their care.
That all being said, I do love what I'm doing now. I come home pretty tired, but I'm usually excited to work with my dogs. It's met with a lot of frustration since we are a non profit and have tours and press events to deal with in addition to our packed schedule of training and husbandry work, but my coworkers are amazing and so knowledgeable and we are like a little dysfunctional family. I generally only do one on one training (we have our "assigned" dogs that we are responsible for then we work other dogs if time allows), but sometimes I lead group training sessions with interns and volunteers who are approved to help with training. Also fun. My weekend teaching gig is wonderful, and I get free use of the equipment after I'm done classes so I bring my guys with me to work to get some good agility time in
In conclusion, dog training in general is just fun for me - group or private/it's just me and the dog. I wouldn't mind a pet store if I knew what I was hired to do from the get go (I actually applied to and was offered a job at a Pet Valu but couldn't take it because I was recovering from a car accident and couldn't lift over 10lbs).