Some paranormal researchers claim that certain ghosts have what is called a "Phantom Scent" i.e. tobacco.

Not all spirits communicate as a full body apparition or a ball of light.  

It is possible that if a ghost of a man who once smoked a certain brand of tobacco, or a lady who has passed on has the scent of lavender is trying to communicate with you. Usually these scents are associated with those who have crossed over.

Some clients feel a warm welcome and a reminder of their loved ones if these type of communication happens.