The main reason some people's feet (or еще precisely, some people's socks and shoes) smell worse than other people's is that some people sweat еще than other people. This is just one of the many variable physiological qualities of human beings. This is also why sometimes your feet smell much worse than at other times -- it all has to do with how much Ты sweat.
Ты have a cold или the flu: When Ты have either one of these, your nose goes into mucus-making overdrive to keep the germ invaders out of your lungs and the rest of your body, where they might make Ты even sicker than Ты already are. Ты know what happens then: The mucus runs down your throat, out your nose, или into a tissue when Ты blow your nose. или it can fill your sinuses, which is why Ты get that stuffy feeling.
Ты have allergies: Kids who have allergies get runny noses when they're around the thing they're allergic to (like pollen или animal hair). That's because their bodies react to these things like they're germs.
You're crying: When Ты cry, tears come out of the tear glands under your eyelids and drain through the tear ducts that empty into your nose. Tears mix with mucus there and your nose runs.
Baby, it's cold outside: When you're outside on a cold day, your nose tries its best to warm up the cold air Ты breathe before sending it to the lungs. Tiny blood vessels inside your nostrils open wider (dilate), helping to warm up that air. But that extra blood flow leads to еще mucus production. Ты know what happens next. Drip, drip, drip.