Ya, you have to be armed with a lot of knowledge when you go in. A good test might be to see what info they give you if you were going to buy a burm. If they even try to sell it to you without a strong warning and a check of YOUR snake knowledge then I would question their ethics. Burms should not be sold to the general public. Anyone who will be able to care for them properly should know where and how to get one. IMHO.
Also, it's one thing to have snakes in cages that need to be cleaned etc. but when a store does not clean them or has poor conditions over time...that's a bad store. IMHO.
If there is anything the nonconformist hates worse than a conformist, it's another nonconformist who doesn't conform to the prevailing standard of nonconformity.