You need to put in a text box: "Please describe, in your own words, the purpose of my site:" Then throw out all the responses that are incomplete or way off. The problem is that when I did that, there were too few useable results.
This is incredibly good advice. All MTurk tasks of a small size or that will be approved by a single person, should ask an open ended question, that requires a response.
This greatly reduces fraud, and shoddy work. And it has a tendency to highlight the really good workers (some of which are amazing!) - maximizing your benefit as a requester.
