I used to firmly believe that there was no such thing as bad feedback. Afterall, writing is about producing a product consumers might want to purchase. I don't write for the art of it. So I try to listen to all feedback and consider it carefully to craft a better product.
Over at page99test.com, authors can upload the 99th page of their work to get feedback. The idea being that any book, if you pick it up and thumb to Page 99, it's a good idea of whether you'd like the book or not.
I don't get much feedback over there, but just now I got one of the all time stupidest things I've ever seen: