ALF offering to negotiate rates.

I agree with what others have said.
Technically, there are usually two things you will pay, 1) the rent that covers the room and board , then 2) fees for the care, that vary based on how much care they need/ level of care. "In theory", these two should be independent. However, in reality, as you fear, could it lead to inferior service as management knows you are paying a lower rate....?

The parallel I suppose is, renting a vacation hotel room from a budget discounter service like Expedia, versus paying more by booking via the hotel itself. In theory one should get the same service either way, BUT...in practice people say those who book via hotel are at an advantage....

So it is a tricky question. It may well be good to have an attorney look at the contract. See how long the lease term is. Also, keep in mind that in many standard contracts there is room for them to increase rates over time.
If they are really undersold with a lot of empty rooms, maybe its fine to take a lower introductory rate? it could be possible that no one in there is actually paying full price rate? then for a short while perhaps its ok?

Tricky scenario. With my dad, we are paying standard room rent, and for his level of care, he is actually at a higher level of care than he is actually taking so we are overpaying a bit. I have mentioned, and the staff have said they could "reassess" him which may bring down the monthly cost a bit with a lower level of care. But I have decided for now its safer to leave it as it is and slightly overpay. I even made it known to the care director and executive director that this is the case....and its ok to keep a slightly higher level of care than he is using to be on the safe side. Anyway, hes likely to need more and more care over time......

Ask to see a copy of the agreement/lease first to review. As JoAnn said, get everything in writing. It might not be a bad idea to have a CELA (certified elder law attorney) review it (or a real estate attorney). If they can't let you see the contract up front I'd walk away.

Just before Mom entered her AL, it changed hands. The prior AL had lost their Medicaid standing and lost a lot of their residents. This meant there were vacancies when the new owner came in. To get more residents in, 50% off room and board was offered for a short time, just the time I was looking to place Mom. That 50% would continue to be in effect as long as Mom was a resident there. Not that there would not be rent increases but it would be based on the lower rate she received. This should mean that any new owners would need to abide by previous agreements. That is what I would make sure of. That any agreement you make with the owner now carries over if there is a new owner and get it in writing. I think as any residence ur laying rent, that residents are grandfathered in and new owners, by law, have to follow previous agreements.

Exactly. You just said it.
You are talking getting what you pay for.