Are Smart People Grumpier?
I may be grumpy, but not smart. I may be smart, but not grumpy. The important thing to realize is that there is a general tendency for the two to be found together. It does not mean they will always be together. I have a really strong chance that I will see my friend with his girlfriend in the store, but that does not mean I will always see them together.
A curious point of interest is that it offers an interesting understanding of how the independent, isolated intellectual stereotype came to be formed.