I recently entered a critique contest. After I received the comments I talked about them with one of my trusted beta's and a good friend who's familiar with my WIP. It took a question from my beta reader to really make me question my sanity?
Did I know what the person who was reading my work wrote? The answer, I'm ashamed to say, was no. I really knew nothing about the person-- had just entered to get another perspective on my work.
I realized after answering this question that I was the one who dropped the ball. If I was sending my MS to an agent, I would research and send it to someone who represents MG Fantasy, not Adult Sci-fi.
Now, the comments weren't horrible, and a few of them were quite valid (and I have made some corrections based on them). But, I would have been better served to know ahead of time more about the person and their writing.
Have you ever just sent work out to be read without knowing anything about the reader? Did you learn anything from the comments you received? Would you do it again, or would you take the time to learn more about the person first?