It's good you're taking her in for an exam as well, since if she does have parasites, vets are legally required to have seen the animal in order to prescribe medication. Soft, stinky poo makes me think it's likely she has parasites. Sometimes they can go off food if the parasite load is high enough as well.
Any fecal is going to be looked at under a microscope, since parasite eggs are microscopic. The best way to have it looked at is a centrifuged float sample, the next best is a regular (which is not centrifuged) float, and the last is direct smear.
A snake will often defecate when soaked in warm water for a time, say 15-20 minutes, and you can collect it and keep it refrigerated until you take it in. If she won't go for you, when you get to the clinic, they'll probably use a fecal loop to try to get a sample. Even if they don't get one right then, keep a paper towel handy, because the act of looping them will often make them poop! Just last week, we had a guy's BP poo on him 5 minutes after we looped her for a sample; I had forgotten to warn him about that!![]()