Animals in a pet store may be exposed to all sorts of things, anyhow. It's up to the buyer to quarantine the new animal. A retail store is rather obviously not going to be able to quarantine.

Proper quarantine for a ball python would be an entire year. Some folks will say 3 months, but the truth is that 3 months is not long enough, and some extremely serious viral diseases can incubate for up to 10 months. So, 3 months is a token quarantine period. How many folks here asking about a retail store's quarantine actually quarantine their new animals for a full year?

No matter where an animal comes from, you should quarantine it, so does it really matter whether a retail store housed some adult snakes together for a short time? It's true, if they had something, they might have passed it to each other, but the odds of you picking up one that contracted something from another aren't any different from the odds of your happening to pick up the originator of the problem, even if it had been kept separate.

Unless you're claiming it's logical to expect a retailer to quarantine snakes for a year before selling them?