For anyone coming along who may not be familiar, here what I understand currently. These types of hallucinations can be hard to tell apart. But ultimately if something smells or tastes other than it should significantly, that seems to be the symptom. So if food tastes rotten, then it’s a gustatory hallucination (as long as it’s not actually rotten). If it smells rotten, then it’s an olfactory hallucination. It’s important not to take the examples given too literally because the symptoms could present differently for many people.
Olfactory hallucinations involve the sense of smell. They often involve an unpleasant smell, and sometimes the schizophrenic person believes (much to his/her embarrassment) that the odor is coming from his/her own body.
Tactile hallucinations involve the sense of touch, and may, for example, involve the feeling that snakes or bugs are crawling on or inside the body. Also, the person may believe an invisible hand or fingers are touching him/her.
Gustatory hallucinations involve the sense of taste. This may be experienced as a strange taste in something they are eating or drinking.