Stupid but believable

When a character does something stupid or short sighted, you often complain about it. But then, you put yourself in said character's shoes and you see that their bad decision was still bad but actually within their character.

Your thoughts?

I only ever complain about it if it's too ridiculous, as in out of character. It doesn't matter what decision they make, as long as it's believable. Besides, people make mistakes all the time, and it's odd if they don't make poor choices. The only problem comes when you depend on these mistakes to advance your plot.