Everyone has to start some where and with some morphs there are subtle differences that can make them hard to tell apart. In this case that is a great example of a cinny pewter, but if it was a poor quality cinny then it might be hard to tell from a black pastel.
I am guilty of buying a couple of animals with completely understanding them. I got my first spider before I knew about the spider wobble. I got my enchi because I wanted to make enchi bumble bees not really knowing what to look for in a good enchi.
I know you weren't trying to pick on them, but I'm just trying to help you see it from the other side. Proper care needs to be learned before purchasing an animal, but you can always learn more about the color mutation afterwards. At the start of the year I would have been hard pressed to tell a normal from a yellow belly, but now I feel confident that I know what to look for in the sublet morphs and can give an opinion. You have to start somewhere and this site is a huge help with that.