Depends on what the food is. I know for Earth foods, they usually have some kind of red or black seasoning on them. Chili powder, paprika, pepper. 'Course, then there's jalapeño, that's green.

But the easiest way is to bug a friend to take a bite first. And if you get too close to it cooking and it starts to burn your eyes or throat, that's a sign too. Trust me, there's concentrated spice so powerful that if you let it evaporate, it'll literally burn you.