Good yellowbelly's are not hard to distinguish from normals, like most morphs yb's come in very poor examples to very nice ones...
http://i968.photobucket.com/albums/a...s/IMG_1463.jpg
http://i968.photobucket.com/albums/a...s/PICT9930.jpg
Here's a side by side with my new line of yellowbelly on the left and another line I won't mention on the right...
http://i968.photobucket.com/albums/a.../ybhcandyb.jpg
Here's a link to help you...
http://www.nextworldexotics.com/hgyb.htm