The chances that an hatchling that has never ate a meal take f/t is very slim, it is their first meal, a learning process and stimulation is often necessary.
As for buying an animal that has not shed or has not have at least 3 successful consecutive meal, I HIGHLY do not recommend, some hatchling can be tricky to start even for an experience owner, they may require assisting and some may fail to thrive, in other word a gamble even more so I you have no experience starting an hatchling.
I personally refuse to sell animals unless they have at least 3 meals in them sometimes more.