I would consider it a rescue if the snake is both, in some sort of trouble that won't get fixed with the current owner, and in poor unsaleable condition. I agree, that if you get known as "the snake person" more snakes are likely to show up than you probably have the resources/desire to deal with.
I used to walk dogs for our local dog shelter, and became the town equivalent. I had to turn a lot of people away. Three dogs in this house is our max (and my max for sanity). I'm a magnet for strays anyway, and have had to bring several to the shelter myself.
Have to say, frankly, I'm just jaded about the whole thing.
People can be so grossly inhumane.
I actually started with a thicker skin; the work became more and more emotionally draining as time passed.