I just got a Leopard Gecko!!
Try browsing the nerd site, and bobclark's. There are a few other threads that have asked things similar to your question. There is a webpage out there (I think it's run by nerd, but I could be wrong, and I can't find it right now) that has a lisiting of what is a proven morph and what isn't.
The NERD page http://www.newenglandreptile.com will give a fairly good run down of what each morph is and what it looks like (it has pictures) if you go to the photo gallery.
I think they are starting to slow down....
I meant he said that it looked like a het for a morph thats wut i meant!
Switching from Mice To Rats -
I don't think there are any sure-fire markings to show a snake is het for anything... I'm not a genetics or breeding expert, though.