Walmart is one of the most popular stores around the United States. I have been there dozens of times and have had pretty good service. The one time i didn't was when me and my mom were checking out and paying for our things. The lady taking our money and bagging the food didn't talk to us at all.
My worst experience was when i wrecked on my dirt bike and needed stitches. My mom took me to the hospital and they put me in the waiting room for 40 minutes. My leg was flowing blood and i was feeling major pain. When i finally got in they weren't very gentle with my leg either.
My best customer experience was when i was at Starbucks in the Bahamas. We ordered our drinks but the guy that was making them was very nice, we talked for a very long time. He was very funny and the next day we went down there to get coffee he bought our drinks for us.