What qualities in people do you find difficult to tolerate?

Arrogrance

I think that willful ignorance is incredibly annoying. I have found that I can at least deal with people who are just simpletons but those who choose to pull a blanket over their eyes and refuse to listen to anything that makes them uncomfortable is something that I find myself just walking away from. I get more enjoyment out of hitting my head against brick than I do attempting to have a conversation with anyone who chooses to believe in fantasy/fairy-tale.

The older i get the less tolerance I have for the intolerant.
and...
The older i get the less patience I have for the impatient.