There are generally 5 categories ...with an additional miscellaneous for anything that doesn't fit . Some prime examples have been included to aid your understanding  
 DIRT FOOD
DIRT FOOD Celery is the ultimate food of wrongness. But also in this category we have beetroot , marrow, marmite !!!!!!
FISHAll categories with the exception of fish and chips and that is only cod in batter . 
SOCK FOODGoats cheese .Halloumi. Feta etc 
BABY FOODSemolina. Rice Pudding. Tapioca etc .
AWFULOffal - absolutely all forms including black pudding / tripe etc   
 MISCELLANEOUS
MISCELLANEOUS Coffee / tea , marzipan