Does anyone bring their own dog on house sitting stays? I know it would depend on the client's approval, but I wanted to see if anyone else has had success with this?

I'm hoping to get a puppy to train as a therapy pet, and after his vaccinations are completed, I'd like to get the chance to expose him to as many different dogs, cats, and environments as possible. Has anyone else stayed at another person's house for house sitting with your own dog? I know the client would have to approve it, and I imagine I'd only be interested in doing this with my repeat clients, but I was just curious if anyone else has done this and what issues/success anyonee has had.