My experience:
I did one in a small convenience store several years ago. The items I had to find were grouped in the app, but the store wasn't laid out that way. That left me wandering back and forth across this little store, which drew attention I didn't want. I was ultimately outed by the manager and told to never return to the store.
I put price-scanning shops on my 10-ft pole list and swore I'd never do another one.
Fast forward to earlier this summer. I kept getting emails asking me to do a truck stop about 25 miles away. I found that very annoying, and I thought, "I'll reply and say I'll do it for $XXX, and then they'll leave me alone." I threw out an ungodly amount that I thought for sure they'd say no to.
Nope. They accepted, and I was stuck doing the shop. It wasn't as bad as the first one, but mostly because 1/4 of the 40 items were tobacco products that were behind the counter, and I couldn't get the prices because the clerk was always standing there.
I wouldn't do another one.
If your path dictates you walk through hell, do it as though you own the place. -unknown