Brown spots on ball python's tail?

[Bogertophis]

I noticed these brown spots on this ball python's tail/belly, which I dont remember seeing before. I tried wiping them off with a warm wash cloth but they didn't come off. She isnt my ball python but im looking after her for my teacher over winter break. She ate a live rat 6 days ago but has not pooped yet, and she does not have any heating or humidity control (not my decision, but i unfortunately dont have the money to buy things for a snake that isnt mine. i asked if my teacher would give me a heat lamp but he said it would melt her enclosure). I'm not sure if these could be causes for this or if its even a problem, but i figured the information could help. Should I be concerned about this, or am I worrying over nothing?

I'm not seeing an issue with "spots on the tail" either, but I am concerned about the care your teacher is providing for this snake. As already requested, more information about the enclosure would help us to help you. Are you saying this snake's home has NO heat? Or just no way of controlling what there is? I'm more concerned for this snake's well-being for the issues of proper warmth and being fed live rats- I hope you'll invite your teacher to join us here so they can learn better methods of keeping a ball python.

And