I have only done it a few times when there wasn't really anything in the description and most of the question (s) are in the title. I try to answer questions that I might know about or can give advice about. The "does s/he like me?" questions are difficult, since I don't know what the person is thinking so I scroll along.
I would have to say sometimes I was option B - If I was in xper grabbing mood - I might have skimmed a long description and then based my answer on question heading but maybe I have been listening to you, I find myself being selective in what questions I answer and thinking about them - My xper gone to crap - I am down from 3k a week to about 700 but in all honesty I prefer it this way.