Paul,
I guess you aren't asking "when is a snake a snake?" We all know the answer to that one, and by the time I recite, "Red touches yellow, you're a dead fellow, red touches black, poision they lack" I really just get the heck out of there and take no chances.
Even further OT, but there are a long traditions of snake scares in golf construction. We have tied dead rattlers to the inside of the tool box on a truck so an unsuspecting worker opening it will have snake "pop up." I stopped that, fearing I would give someone a heart attack.
On the plus side, when my son had his sixth birthday, and after every other kid in his class had elaborate parties, I was able to take his friends out to a construction site and let them each drive (with help) a bulldozer, and his was the party of the year.
The bulldozer is of course a perfect ride for kids of all ages, but as the operator was showing one kid how he knocked down trees, they found a bed of rattlers in the roots, which he killed by dropping the blade on them. We packaged them up in plastic bags so each kid could have a dead rattler as a party favor. They were estatic, but the mom's were not so amused when we got home....