I truly believe it's important to try and see the best in others, even if it isn't always obvious. At the same time, there's a certain low bar that we should all be jumping over once we've reached adulthood, and felt a couple of the hard knocks of life.
This usually involves simple things, like being polite, or cleaning up after ourselves. Sadly, there are too many individuals out there who prove time and again that they are not willing to participate in being courteous.
A recent Reddit thread rounded up some of the most infuriating examples of this. It's not always the fault of parents when people are douchebags, but it's easy to feel like their behavior is a testament to a lackluster upbringing. There are few excuses for all the awful things listed below, but there are plenty of grim explanations if you really want to dig hard enough.