Foods that spoil quickly, like raw seafood or dishes with mayonnaise left out of refrigeration, can become unsafe to eat.
Foods that are messy or hard to eat can be inconvenient for guests.
Many people have allergies or dietary restrictions. Bringing dishes with common allergens can exclude guests or pose health risks.
Pungent foods can be off-putting and overpower the aroma of other dishes
Dishes that require special utensils, last-minute assembly, or extensive preparation can be inconvenient at a potluck.
While introducing new foods can be fun, unfamiliar dishes might not appeal to everyone and could go uneaten.
Not everyone enjoys or can handle spicy foods, which can limit the number of people who can eat the dish.
Too many of the same type of dish can lead to redundancy and wasted food.