Actually, NorCal has a point from earlier. A lot of the mistakes are made out of the simplicity. It's really no excuse, though. I, as an example, work at a local pizza place for one of my jobs. I make maybe one mistake all night, and always claim responsibility. I only blame the customer when it IS their fault, i.e. standing at the counter demanding I change this thing, no I changed my mind, I don't want onions, etc. But even then, I'm a cordial motherfucker. I smile, tell them ok, and tell them to have a nice day. When they call back and complain (which doesn't always happen, but will occasionally), I'm nice and sincere on the phone. I figure it's my ******** bosses job to be a jerk, not mine.
However, it is greatly appreciated when someone is nice back, as most of my customers tend to think I'm lower than them just because I have a job and don't leech off the government like roughly 65 per cent of them. And, that's not me being a dick, that's me being truthful.