Actually, no not really. I mean, aside from the occasional cart that runneth over that I see before they see me, because they can't see over the top. Or if I am looking for the "shortest" line to check out in...then I'll glance at what is in the carts.
I actually am more aware of what other people might be thinking of the odd variety of items in MY cart. It isn't always a balanced cart, if you know what I mean. I do shop sales and stock up things sometimes, when it is a good price, especially if some other 'perk' is involved. For example: I rarely buy my kids sugary cereals (for one, they don't eat cereal with milk for breakfast, so it is almost just snack food---but I happen to like some of them)... Winn Dixie had a sale on them a week or two ago (buy one get one free), and at the same time it was on their "fuel perks" bonus list. So I got discounted snacks (bought the two boxes) AND 5cents per gallon off my gas. There were a few other "snacky" items that were on similar specials, so I stocked my pantry. Now, generally, I don't do a lot of shopping there, but I wanted to take advantage of the sales on the snacks and the bonus fuel perks available, so I popped in and got ONLY the items that fit that list and that did not need refrigeration---since I had to hang out in town until my kids finished their 2 hours worth of martial arts classes.
If anyone had seen my cart/basket, it was loaded with pretty much nothing but prepackaged snack food. But I earned about 30cents per gallon off my gas on my next fill-up, and I stocked snacks for several weeks. Then I picked up my kids and went to my "regular" grocery store and bought Boar's Head deli meat, whole wheat bread, salad greens, cucumbers, bell peppers, apples, strawberries, nuts, Greek yogurt, etc. The people who looked into my cart THERE probably thought I am a health nut. LOL
So I try not to be judgmental if I do happen to notice (usually the person in front of me in a long line) what is in someone else's cart. Who knows how they shop. But I agree with the person who mentioned that it is interesting to note if the cart "matches" the person pushing it. Sometimes it seems a given what I expect to see in the cart (all health food/organic or all junk).
ETA: Newsflash people--just because someone is buying frozen pizza or microwave dinners, doesn't mean they are alone. We buy it for when me and hubby are going OUT for dinner, and the kids make something frozen at home. Lots of frozen pizza means many date nights, at our house. ;)