There are only a few places in my town that I've been able to use Android Pay. At Walgreen's and McDonald's, they haven't seemed to care at all.
At Subway...The first time I used it, I had seen the sign saying they accepted it as I entered, so I told her I wanted to pay with it. She told me they didn't do that and I referred her to the sign on the door saying that they did. She figured it out pretty quickly. The next time, that same girl was still there, but wasn't the one to ring me up. She had to explain to the person who did ring me up that they have to hit the credit card button for it to activate the card scanner that sits on the counter next to the register and the scanner handles the rest. The most recent time, that same girl was there again, but not my cashier. I told the girl ringing me up that I needed her to press the credit card button on the machine. She was confused, but did as I asked. When I held my phone to the scanner and it went through, she freaked out. "OMG! No way! Did you see that!? He just paid with his phone!" I had to explain to her that that other girl already knew all about it. Haha!
That's the only real significant experience I've had with it.