I'm not in any way trying to negate any of the positive pieces of informaiton given here, or trying to offend anyone, but I would like to say that purely IMHO, I don't think a lot of hobbyists really know what mites are like. Until you've had personal experience with them, it's really hard to know. I'm willing to bet there's a lot of captive pythons out there with mites, whose owners would swear otherwise. Every snake that has ever soaked in my care, has been a new acquisition, and has mites or ticks. I'm not denying in any way that they soak for other reasons, but I'm just saying, the little f***ers are REALLY REALLY hard to see...and they're not always black. Juvenile mites are white. Even harder to see, especially as they're SUPER tiny. If an animal is still soaking on and off consistently after a couple of weeks, I'd be putting plain white paper in the cage as a substrate, and looking for the black dots. Also, check for them in the water bowl.
Mel x