Many think so, mostly due to how we are raised to perceive them. Others, think snakes are beautiful. Here is a pic of the snake in this topic. He's gorgeous! Look at the coloring and huge eyeballs. Cool tongue.
I'm going to have nightmares. I actually can handle and take care of "domesticated" snakes. It's just the ones in the wild they seriously freak me out. If I see a snake outside of its cage and don't expect to see it, I run from it. It's just a weird phobia of mine that I cannot explain.
Some snakes are venomous. So, unless you are familiar with which one are, and which are not dangerous, then its a natural instinct to run. Snakes count on that fear that just about every animal has towards them.