I don't often have to buy a lot of things at one time at the store so I like to use the self service check out because it's quicker for me. My biggest pet peeves about those checkouts though is when someone doesn't know how to use it and stands there looking like an idiot without asking for help (or takes 2 hrs to process their order of six items), and when someone gets in line with a flipping cartful of about twenty plus items and then take forever to scan them all. If you have a cartfull of groceries, go to the other checkout lines because the self service ones are for SMALL ORDERS ONLY and twenty items is NOT small. Irks me to no end when someone thinks that's okay and holds up all these people (like me) who are standing there holding about three items and waiting on their sorry behind to get done.
And I always return a cart when I use one and clean up my table at a fast food restaurant. It's a force of habit by now and I've also worked fast food before so that makes a difference too. My current problem is walking through a store and starting to pick up or refold clothes as I walk by since I'm working a part time retail job through the holidays. It's a new force of habit to clean up the area as I walk by all the messes and I really need to break it after the new year, LOL