I've done customer support for delivery companies, although not UPS, and the caliber of the drivers is definitely something that is very variable. Sometimes I'm amazed they even have a license.

There are certain properties that they seem physically incapable of locating, even though there doesn't appear to be anything particularly interesting or odd about the address, and I can find it easily by googling it. There must be some kind of temporal anomaly that I'm unaware of. So anyway, that job sucked.