What did you do?
I have to admit, it's happened to me a few times.
I didn't ask for a refund. Here is why:
1) If I know better but let my greed get the best of me then the small price of a WSO is more than worth the lesson.
2) Sometimes it turns out that the info is good but it doesn't meet my goals or current schedule. However, that's the risk I take and it's MY RESPONSIBILITY not the seller's.
So instead of asking for a refund, I move on with my life.