What do you know about ghostbusters?

I have a young friend who, with her partner, is hired to rid a place of ghosts.
I asked, “How do you even start?”
“We ask if the client wants all the ghosts gone, or just, for example, Uncle Charlie? The client usually doesn’t want all the ghosts gone, just ones who are a nuisance.”
“How do you know they’re gone?”
“What ever was disturbing the client no longer happens.”
“What do you do to get rid of them?”
“We talk to them. They are usually stuck here for some reason and really would like to leave.” We tell them what the situation is and talk them into leaving.”
This confounds me no end. Has anybody else had any experience with this sort of thing?