Possums are known to dislike certain smells, which can be used as deterrents. Some smells that possums hate include ammonia, garlic, hot peppers, camphor, onion, and naphthalene (found in mothballs). These odors can be used strategically around areas that possums frequent to discourage them from staying or returning. However, it's important to note that using these smells as repellents may not provide a long-term solution. For effective possum control, it is recommended to consult with a professional wildlife removal specialist who can provide expert advice and assistance in possum-proofing the area.