Do you let people hold the snakes and spiders even if they aren't going to buy them?

Hard No indeed .

Nope, that would be a possibly danger to the animals/ inexperienced people handling them. For everyones safety, I'd say that's a hard no.

As a customer I have been able to hold hamsters and Spiders before without buying them, as I was asking questions about said pet.

I wouldn't think they would.