I share your frustration, most of us here do. I've personally seen the damage done by poor pet store advice and the havoc it wrecked on the snakes. Having said that though, in this day and age of computers, it's still encumbent on the purchasers to do as much research as possible. Here's a hint from my own "playbook". Don't ever listen to one source or even two. Research your fingers off. Don't believe much of anything until you first verify the source actually knows their stuff and you've found the same or very similar information from two other independent sources. You don't have to rude to anyone but you have every right as a responsible snakekeeper to question why that piece of advice is sensible and how that person gained that knowledge they've shared with you. Anyone that can't back up a statement isn't worth your time to listen to, me included.
As far as pet stores, some get into it for the cash, some start with mammals and get into reptiles and totally blow it. Some, far too few, are wonderful places that do a great job. Wish we had more of those.