I've had plenty of snake dreams too.. they are quite common actually; you will find that our history is ripe with snake symbolism... even down to the depiction of our dna...
(my my... look at how our dna is depicted here.... very closely controlled & trapped in a snake pit...)
Soooo... the serpent can represent that which we consider evil... tainted... destructive... tightly controlled and trapped.. and the "reptilian" part of our brain... (considered so because it is well developed in reptiles) the pineal gland... deals with our controlling instincts, our anger and fear... (remember the serpent was the one that tempted eve in the "garden of eden"... whether or not you believe that story to be true, it has a deep symbolic resonance within our psyche..)
So a dream about running from snakes?
Well, everyones dreams have their own meanings so it's hard to truly pinpoint based on a general description but...
Maybe you feel as though you are trying to get away from evil... maybe you struggle handling even your own "demons" face on.... tons of people have this problem... especially in todays world.. (of astrological note: the nodes can be said to represent the dragons head and tail.... dragons and snakes are often intertwined, symbolically... and the north node is about progression... so facing things... head on... will give you progress....)
By the way, I consider it to be a good thing that these snakes are not your friends in the dreams
better to run from evil than to mingle with it, ya know?
In my opinion, Jung did dreams the best justice, so if you are curious about the meaning behind your dreams... pick up some of his books.... way way waaaaaay more insights than you could gain from a typical dream dictionary..