I work weekends at Tesco, so where to begin...
Firstly, regarding scan speeds, we're watched on how fast we scan, needing to average a certain number per hour. Though to stop people just blitzing the items through as fast as possible, time spent not doing anything, as well as the time difference between hitting the 'total' button and payment being processed is also timed to give an overall rating. Most cashiers for this reason sign out whenever possible so that they aren't on the system and having time counted against them.
The items per hour thing isn't used for pay or anything, just every year there's a performance review style thing, they just look over the figures, see how you are compared with the average, if you're close then its all ok, if you're somewhat lower they suggest ways to get it up, and if its too high, they say slow down.
We also have a mystery shopper test, pretty obvious. People go round the store and mark it. For tills there's 24 marks available, ranging from simple things (6 marks for saying hello, goodbye and smiling), but also making sure the till is tidy, you look presentable, have a visible namebadge, offer carrier bags, offering to help pack, and asking if they have a clubcard.
So you get asked these questions at Tesco because we have to. Some people keep bags in their pockets, so even if it looks like they don't have bags, I ask in case they do. Or their husband/wife does and they're just grabbing something else. In which case I wouldn't start packing.
Personally, when asked to pack, I'll do it sensibly, cold stuff together, heavy stuff at the bottom, etc. In any shop there's going to be people who just bung stuff in however, they just do the job for the money, and to an extent I do to, but I put extra effort in because I'm still representing the company, and I want us to look good. Plus soon I'll be getting shares, so the better we do, the more money I get through that
I know I'm personally not the most talkative guy, so won't try to start a conversation but will continue it if the other person does. I'm often on the basket till (Which is labeled as such), and it ranges from being massively busy with a huge queue to nobody there for stretches of a time. If its empty, I don't mind people coming in with trolleys that don't have much stuff in. Normally its older people who just can't carry a basket despite having just a couple of items, but when its busy I will generally turn away people who have silly trolley loads. Also, I've noticed so many times people queuing for the self service tills right next to me while I'm sitting with nobody to serve, same for the other person on the checkout next to me. They often have to be ushered over by a manager to try and reduce the queue! I don't have a problem with the self service tills myself, though only 1 person to man 8 of them often isn't enough, or the person that is manning them starts chatting to another customer, and ignores all the red lights. As I'm sitting right next to them doing nothing, they often ask me to help, but I'm not trained to use them so have no idea how to fix most problems, though apparently I'm getting the training soon. Yay!
So, things which annoy me? Not all that much, really. I don't mind too much people being on their phones, though eating stuff as they go around is a big no-no. Customers getting angry with me when their card is declined is one.
Also, people taking something off the shelf which has no label on. Obviously if its just a damaged barcode you can't really blame them, they shouldn't have to check everything they pick up to see if the barcode works, but a jar of pasta sauce with no label on at all, while all the other ones on the shelf have labels? What am I supposed to do with that?
Equally, people dumping cold stuff they don't want anymore at the end of the tills. If its non-chilled then its not so much of a problem, we have people to go around and collect them all up and stick them back on the shelves, but cold stuff needs to be kept cold! Give it to someone, say you've changed your mind! We won't hate you for it! We will hate you if we have to waste it because you hid it out of the way though!