My guess was that the Good/Bad rating is to help with some sort of Machine Learning going on the background. E.g. the way I draw my Ampersand might be slightly different than yours, so if either or both of us see the result we were hoping for (&), that should get our Good rating. If it returns an (8), it may or may not deserve a Bad. If something way off appears as a top result (^), that would be pretty Bad.