I go to Starbucks every single morning. I buy a cup of coffee, and something to eat. I tip. I'm polite and friendly; I don't leave a mess and I don't leach too much wifi.

One morning I get there and there's a long queue. People don't know what they're doing - they're taking ages looking at the menu and choosing drinks and trying to order them and arguing over the drinks they're eventually given. And they all get a pack of beans, ground to how they like. And then I notice that they're handing in a coupon from a newspaper.

So: I don't get free stuff; I do get worse service; staff get a bunch of rude people who are only after the free beans. I was grumpy. Staff were grumpy.