I groom part time in three different places.
My house, of course I'm responsible for everything. :)
At the clinic, I come in and groom, sweep up the hair in my area and go home. I'm done before the clinic closes and usually before most of my dogs go home. Because of that I don't do any deep cleaning. I do try to throw laundry in if it's piled up. If I see a boarding or hospital dog has messed a kennel or something, I'll clean that up. I try to help where I can, but because of my limited time there, and all that goes on, I don't end up doing a lot more than just grooming.
If I had a separate grooming room, I'm sure I would do more deep cleaning, as it would all be my mess.
At the salon, I stay until all the dogs have gone home. I was never told I had to do that, it's just what we all do. While waiting, and as they all go home, we pull kennel trays to clean them, shop vac throughly, empty trash cans and do laundry through out the day. I am not compensated for it on my paycheck. They do buy dinner on Wednesday nights and lunches on Saturdays(the only days I work there) and it's not unusual to find something they've bought for one of us if they see something they know we would like. So basically, they are super nice people. :) If I am finished early and grab a dog to dry or prep for someone, I am usually given a little something as a token of appreciation at the end of the day. I figure if I'm done, with nothing productive to do, it helps everyone if I step in and help someone else get finished.
I think it I was expected to do any kind of deep cleaning, something that took more than half an hour, at any job, I would expect some kind of compensation if I was being paid on a commission basis.