Usually I answer questions I think I know or ones that I feel like I could offer some insight and advice to the QA. I also like to answer personal questions where they ask people about themselves. I don't really look at who the QA is so I don't base it off of that.
I answer when I see a person REALLY needs help, I give my attention to the question and read it carefully, long or short I still take the time to read it and give a thoughtful answer. Many people disagree with my answers which kind of annoys me at first because I am very honest on here and lately people prefer to sugar coat things, it doesn't work with me like that.