Marion, One way you could utilize the senior-residence community for practice, without jeopardizing your standing as a professional music provider or as a musician, might be to find a small adult foster home near where you live that has a piano. Many of these smaller homes (3 to 6 residents) really do not have a budget for paid entertainment, but they might enjoy you coming in several hours a week to practice, especially if/since you will be practicing your nursing/retirement-home repertoire. Or you might find a couple of them that would let (encourage) you to come in once or twice a week to practice.

I doubt that you would develop a reputation as a second-rate musician because a handful of people heard you practicing your new numbers -- especially if you discuss that potential problem with the owner ahead of time. The same goes for the issue of being cast as a "volunteer."
You could make it clear that part of your symbiotic arrangement is that your playing for them "free" is not to be publicized.

Just a thought.

Genie