just so damn beautiful and so creepy to most of us I like to watch that African guy that catches snakes he is a tattooed marvel
They can be warning colours of course. But they can also be camouflage, since they may prey on specific creatures, and some of those may have colour vision which is quite different from the spectrum we see. Also I think that some of the photos may have had a little Photo-shop help.
Three constrictors and the rest pretenders. They might be mimics of a real dangerous snake. Or they could be used a blend in color.