What is it about bones that makes them stink when you burn them?

The bad smell is likely due to the burning bone marrow which is a tissue loaded with blood cell precursors and proteins. If you take a piece of meat tissue and burn it to a cabon crisp, it will smell up the area as well.

It is probably the particles that get into your nose and lungs. It’s not just a smell, although @gondwanalon has some good tips, but the actual unburnt parts.

Bone marrow is basically human blood. burning human blood is number one on the bad smell list.

I’m going to guess it’s the proteins, colagen, and other such nutritional stuff. To contrast, my experience has been that bones that have been boiled for soup first, then dried and burned, smell perfectly fine.