I agree. There is huge risks in damaging their development, and what is the purpose? You are deceiving the customer on the true genetics, by manipulating the incubation environment. That is definitely a morality issue on both levels for me.
As for being possible with ball pythons, yes. If you want to make BPs with pattern deformity, which typically comes with other physical deformities, you can spike the temps. In studying the results of incubation and developmental issues with ball pythons, there can definitely be some deceiving appearances, many people unknowingly view as "dinkers" or potential morphs, that inevitably don't prove out to take on their appearance. After looking at many animals that have not proven genetics over the years, there are definite signs you could call "markers" that show it is the result of an incubation or developmental manipulation. This appearance can also be seen with mutations or combos to an even more surprising appearance. I see them on here quite frequently, but refrain from commenting as not to dampen or spoil someones hopes for their ball python "dinker".