Generally, not always but most times the animals at pet shops are wild caught and are sick and or not eating and often carry both internal and external parracites. Most of these animals die making your first reptile experience an expensive an un-pleasent one. Some of these animals can be cleaned up but my the time you pay the vet bills you could have bought maybe 2 or 3 captive bred animals.
The key is to pick a species you like best and do a tone of reading about it. That way when you go to the pet store you may very well know more then the clerk. Don't forget that pet store employees are only as good as their training which is often very limited. The clerks at pet stores are sales people not herpetologist. And they sell more then just reptiles so what often happens is they know a little about everything in the store but not much about anything.
Pet stores will also try and sell you every possible little thing they can so be aware of what you actually need and what you don't really need.
Anyway long story short, most pet store animals are wild caught and that is just bad. Do your home work and you'll be fine. Ask us lots of questions about everything and anything.
Here are some good questions to ask a clerk to gage their level of knowlege,
1. Is it wild caught or captive bred? If captive who bred it?
2. How old is this animal?
3. How big will it get?
4. What does it eat?
5. How long will it live?
6. Does it need any special lighting?
7. Where does it come from?
8. What is it's native habbitate like? Wet, dry, what?
9. Is it a male or a female?
10. Do you carry food for it and what does it cost to feed it for a month?