>> Any others out there with dragons with favorite colors?
Oolong is a green-eater. He gets Rep-Cal adult pellets, & we quickly learned to put in very few yellow & no red pellets at all, because he'll scarf down the green ones, occaisionally sample a yellow (especially if hand-fed), and absolutely refuses to eat anything red.
Our vet was very concerned the first time she saw Oolong, because he pooped on her floor & it was a vibrant kelly green (pretty much exactly the same colour as the green Rep-Cal pellets). It took me a minute to realize that it was the colour that was worrying her... she felt much better after I explained that his favourite non-live food is green Rep-Cal pellets, which are, apparently, just oozing w/ artificial colours. ;D
The vet later told me that she was amused to find that the pinworms that showed up in his fecal exam were stained the same shade of green. 
If anyone has a beardie who prefers yellow and/or red Rep-Cal pellets, I'd love to trade ours for green ones. :} I wonder if Rep-Cal will ever offer individual colours?