Big Sam told the Daily Star Sunday: "Dioufy is a scallywag who loves life as well as football. Mego seemed to think he couldn't handle his type of character - and we know he does have a bit of a temperament problem.
"I didn't think he was difficult to handle. I looked at him as a very gifted player who will create opportunities for other players to score.
"He should score more himself, although he is capable of getting a goal.
"He made us better at Bolton and he will make Sunderland better after last year's struggle to stay in the Premier League. Dioufy didn't want to stay at Bolton and he was in the last year of his contract. He had a small fee attached to him of around two million pounds.
"When you look at the money being spent on players like Robbie Keane, who has moved from Tottenham to Liverpool for about £20million - and he is older than Dioufy - then Sunderland have got a steal, as long as he does for them what he did for me.
"And look where he got us. He first arrived on loan at Bolton before signing permanently, and we finished sixth, eighth and seventh in the Premier League and also reached a Carling Cup Final."