Well but horses don't fly, they don't spit fire, they're not one of the most mythological intelligent creatures...
I don't know, I don't search for books with Dragons but when I come across one I don't mind at all. But as I previously said it has to be correctly done.
*EDIT* Well you have Pegasus that's cool too I suppose, you have Hippogriff/Hippogryph, they're cool too, I wouldn't mind to read something where any of these creatures were in.