The things you have stated here are why most people on this site dont have much trust in pet stores. Most of the people that work in the stores dont really know what they are talking about. They are like the used car sales people of the reptile community. Im not saying everyone who works in a pet store doesnt know anything.
This is just an example, the first ball python I owned was back in 1996 and I was told by the person who sold it to me that it should only be fed once a month, and all i needed was a 20 gal tank and a uth. I didnt have a thermostat also nothing about humidity was ever told to me. After a year of owning that snake it was under 300 grams. I ended up moving to a place that didnt allow pets and a guy I knew who had many reptiles took it off my hands... But pet stores are not known for healthy animals or for advise on keeping them...