Is everything with a foul odor, such as the smell of feces and urine, considered impure? And what is the ruling on a garment or food that has an odor similar to that of a toilet?

The impurity of a garment or food is not determined by the presence of a smell of impurity in them, because the smell of impurity itself is not impure, just as the smell of flatulence is pure. Some scholars recommend washing a garment that is possibly impure, whereas the default is purity unless impurity is overwhelming.