"I've done what he's done," Sheen told the New York Post at a TV programmers convention in Miami, where he is trying to sell his new show, a TV version of the movie "Anger Management."
"I've replaced a guy [Michael J. Fox on 'Spin City']. It's so f------- hard, you can't believe it," he said.
"It's all you're thinking about, and you're surrounded by these ghosts. So, hats off to him for doing the best job that he can."
That said, Sheen believes the show ought to die in May when the current season ends.
"I don't think they should go on past this year," he said. "I just think that people are there because there's nowhere else to go -- yet."
Sheen, TV's highest-paid actor when he was fired from the series last spring after one too many angry outbursts about the show's boss, Chuck Lorre, has still not forgiven the powers that be.
"I don't think that [Kutcher's] working with the best writing because Chuck is doing too many shows," he said.
"He and Jon [Cryer] and Angus [T. Jones] deserve better material. They deserve what I had for the first five years. I don't want to harp on them. Let the clueless stay clueless.
"I was a puppet there for ratings. But, whatever -- I don't care. I've moved on, and whatever they're doing there is none of my business."