Something that's odoriferous carries a smell. When you hear someone use the word odiferous, just hope they're not referring to your breath or armpits.
Odoriferous is made up of the word odor, meaning smell and the Latin ferre meaning "to carry." Something that's odoriferous certainly carries a smell whether it's onions or roses or a pile of dog poop. Odoriferous has a less well-known second meaning; something that does not take your morals into consideration can also be odoriferous, or morally offensive. Many people consider animal testing odoriferous because of the harm it does to animals. The might call it odoriferous, or they might say it just plain stinks.