I feel like the type of person who doesn't know/care about the difference between poisonous and venomous would be the exact type of person to 1) possess a deadly snake and 2) carelessly and terrifyingly misplace it. Which makes the sign even more credible, somehow.
Snakes are pretty wily. We used to have a ball python that would escape with some regularity. It made things interesting. You never knew where she would turn up—coiled around the phone, on top of the bookcase, in the bathtub, in the bed, in the dishwasher...
I quickly figured out my ball python's favorite hiding spots, but the first time she got out, we couldn't find her for a week. My mom woke up and she was in her bed lol. Fortunately my mom has always been comfortable around animals, she didn't even flinch, just shouted at me to come get my snake.
I had a ferret that was always looking for new places to sleep, he'd scare the shit out of everyone. You'd open your drawer for socks; ferret. Open the cabinet and take out a pot; ferret. Open the curtain to the bathtub; ferret. Pull your pants up; ferret.
If you bite it and you die, THATS poisonous
If it bites you and you die, that's venemous