looks weird....but could be due to the position draped over a shoulder/neck.
It could be a snow or have snow as part of its makeup..could also be a translucent too..or just a very reduced pattern pastel or hypo...
If you are not planning to breed it and need to know its genetics, buy if it seems healthy to you (the picture is hard to tell..may be on the skinny side, but again, the pose makes it very difficult to see). Any healthy dragon makes a great pet.
Snows tend to loose more and more color and pattern as they get older, so it could be in a transitional stage, though from the picture, it looks nearly or fully grown. But again, hard to say, giving different rates dragons grow though most reach their full growth by 14 months of age.
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PHLdyPayne