why does food smell gross when I have a cold?!

Your nose is lined with cells called olfactory cells. These cells help to detect smell. When you have a cold, these olfactory cells are blocked partially or fully from nasal inflammation (Swelling) and mucus/ snot. This will affect the way you smell anything, especially things with stronger odors such as food.

Try taking some ibuprofen (advil or motrin) to relieve nasal inflammation. Your stuffiness/clogged nose is most likely due to the inflammation not the mucus/snot. This could temporarily change the way you are smelling food and may help with your stuffy nose.

Same reason the minute I get a cold I can't taste anything. Your nose and your mouth are
connected. How many times have you not been hungry but then smell something cooking and your mouth just starts to water and you want to eat it? Smell forms part of our ability to taste.75% of
what we perceive as taste is actually smell. The odour molecules from our food give us most of our taste sensation. When our noses are stuffed up we can't smell therefore we can't taste. The odour
molecules remain trapped in our mouths and what we smell is usually a mixture of them and smell of our own mucus. Not very pleasant but that is the way the body works.

Science class

people usually loose there appitie when they are sick, for me the food just tastes gross if im that sick and i dont want to eat. but your probably different and you think that it has a gross smell instead..