Thankfully I don't have any weird experiences myself, but there is a KFC sort of near to me that was on my route home from then-work and I'm a lazy fuck, so I'd tend to swing by now and then for a bite to eat from there because it was usually late and I was tired as hell from a 12 hour day.
When you start to become a semi-familiar face you natter with the staff while they prep your order and they always seemed pretty nice and chill, the manager was a good sort who looked after their staff and would pounce the second he'd hear raised voices, usually to bat for his staff.
One day, I drive up to the drive through only to find him serving me instead of doing what he normally did which was paperwork in the back, and normally we'd exchange brief pleasantries.
Turned out the poor sods had just had endless shitty customers at the Drive thru and front serving desk all day, with people complaining over the slightest thing or honking horns if stuff took longer than 30 seconds. One customer had been so abusive to the girl on the Drive Thru that she'd become an emotional wreck and wound up being sent home early, and so the Manager was ready to smack the next person who kicked off.
He basically went on about how others had also kicked off at his staff all day, trying to cadge free stuff off the back of their incorrect orders and he wished that more customers were "just like me because you don't care and don't kick off if stuff goes wrong, or you have to wait."
So, because I'd heard him have a moan and agreed with him (seriously, never treat service staff shittily, even if you can see them prep your food) he promptly gave me the survey discount of 10% for being such a good customer.
One that I got pretty much permenantnly from then on, which was nice. He wound up moving on after a while into district managing and last I saw him, he was running several branches of delicious chickeny goodness.