Clueless category: CSR. When a person using an assistive device asks where something is, please don't just hare off in a sprint and make them chase you all over the store. Try, "Would you like me to show you or would you like me to get it for you?" If you can go get me that particular brand and size of hot sauce, it will be so much faster. If the person says, "I need to see it, thanks," let them set the pace, not you.
Clueless category: CSR. If I introduce myself as Dr. Lotus, this is a clue by four that, even though I know you will need my given name and I will give it to you, I have made my preferred form of address clear, and it is NOT OK to call me Whitey. And it is White, not Whitey, anyway.
Clueless category: CSR. Don't just read your script in a monotone. At least pretend you are having a real conversation with a real human being. If you can't do that, the customer will think you aren't very bright and things will go slowly.
Malicious category: corporate. Making life double difficult for your employees by requiring mandatory charity or credit card solicitations, making "Excellent" the only acceptable feedback -- now that I know this happens, I always ask -- making unreasonable time demands, and otherwise treating them as droids who are out to rob you blind. Treat them as people. Nice people.
Malicious or maybe clueless category: corporate. When you are buying those carts for disabled people, ride in them for a while. They are jerky, bumpy, and don't turn in an aisle (mostly). Do YOUR shopping from one for a month. Then decide. Mobility issues caused by obesity are not the only reasons people need these carts now and again. (Those people aren't as affected by the jerking and bumping, it seems. No judgment on them.) The person using an assistive device should always be offered help by passing staff members: nothing I ever want to buy is at eye level. "Can I reach something for you?" when I am clearly struggling, is something I appreciate.
These are all I can think of right now, but there are more. Mostly they all have to do with putting one's self in the other's shoes, being polite, and recognizing the limits of the position the person is working in.
Can you tell I had an injury not all that long ago? <g>