Well, if by "rescue" you include snakes that desperately need an upgrade but aren't so badly neglected that they can't be turned around with a little TLC... then I have four. None came with mites, none came in sick, three were obviously underweight but not life-threateningly so. Two came in with stuck shed, retained eyecaps, and scars from rat bites. All four were free.
I also have three dogs from a rescue, one of which has cost over $6,000 in vet bills between his surgeries and seizure medication. Yes, he's worth it.