What happens if you fail a quest?

I was skimming through the Stats screen in Kingdoms of Amalur: Reckoning when I came across this puzzling bit of information:

Personally, I wasn't even aware of the fact that failing a quest was even possible. Now, being a completionist, this concept has me worried. I know in this article, they mentioned being unable to lock yourself out of content. However, I'm worried that failing a quest would conflict with that concept.

What are the consequences for failing quests?

There are several ways to fail quests.

Firstly, credit to Sterno, there are a handful of "1 shot" quests like Oh, the Indignitaries . It's usually trivia or logic puzzle quests that have this condition that I've encountered.

Secondly, you may fail a quest if a quest NPC dies. As you probably know, you can turn on Hostile Mode and attack friendly NPCs. Besides main storyline NPCs, I've found that pretty much everything is fair game, and you can completely lock yourself out of certain quest lines by killing respective quest NPCs.

Thirdly... (pretty big spoiler here)

You can lock yourself out of certain faction quests through betrayal. For example, towards the end of the Warsworn main quest line, you may choose to betray them. By doing so, any remaining quests you have with their faction will immediately fail as the NPCs are irreversibly hostile towards you.