Why does flatulence vary in temperature and smell?
Kind of a bad question but I'm doing my best to answer.

First, the smell will depend on what goes in - primarily a function of what you ate, and conditions in your gut (including the mix of bacteria).

Next, if you ate something containing large amounts of capsaicin (the chemical that makes chili peppers spicy), it's going to "burn" on the way out. Overconsumption of capsaicin can irritate the intestines and cause diarrhea.