"You have to control the legacies of these legends ... you have to control it in order to prevent other people from abusing it," Richman said.
Still, using a dead celebrity to sell a product isn't without risk.
Steven Levitt, president of New York research firm Marketing Evaluations Inc., which tracks the likability of dead celebrities, said that Lucille Ball, Bob Hope, John Wayne, Johnny Carson regularly top the most likeable list.
But not everyone is so marketable, Levitt said. "It depends on what the person died with, how much baggage, and how long they have been dead."
Michael Jackson is a case in point. Jackson's consumer appeal waned while he was alive because his controversial lifestyle took a toll on his image.
"But people tend to forgive and forget once the person is deceased," Levitt said. "We are almost certain Michael Jackson's likability ratings will get a whole lot better than they ever were when he was alive."
Meaning Jackson, like Farley, could turn into quite a pitchman, now that he's dead.