I guess you get used to it. It is pretty hard "for me personally" to not know if it is or is not a ball pythons. Ball pythons just look like ball pythons to me, no matter the color. Snakes like burmese or retics, when they are small, usually they are pretty skinny but long with a typical python head by the time they reach ball python full grown size. Full grown 5ft Ball Pythons will be thicker then a retic or burmese at 5ft. I am no expert either, but ball pythons just have that ball python shape to them... wow, it is kind of hard to explain. I have never really thought about it before.

Very rarely is a snake up for sale that they do not have the species and morph explained with their sale price. If this is not the case, you could ask but why would someone not label it? You will get used to it as you explore and learn more.