Generally speaking, it seems that chess players are either grumpy or just wierd. Personally, I think I tend to be in the grumpy camp. In fact, my wife has to remind me to not be so negative all the time.
Now comes a study about the benefits of being negative. This article explains some of the findings of the study such as being in a bad mood makes you less gulliable, improves your ability to judge others and boosts memory. Negativity can also "trigger more attentive, careful thinking paying greater attention to the external world."
A couple of other good things about being in a bad mood are: less likely to make quick decisions and less likely to make mistakes during recall.
That's all good for chess improvement!
It's good to be in a bad mood.