Fatty, sugary, and salty foods do not make you feel good shortly afterwards. They make you feel bad. If there is any sort of bad sensation at any point, you shouldn't be consuming that food.

There's something to the cancer argument but like I said previously, the determinates behind that stuff are so hard to figure out - and I would say that likely, the foods that keep us feeling good day to day - ALL DAY - are not the ones causing us to have cancer - but I'm no scientist.