The former Red Devils skipper has been left frustrated by the club's dismal start to the season and is appalled by the lack of team mentality in Erik ten Hag's side.
Keane told the 'Stick to Football' podcast: "I think it was after the Twente game (in the Europa League) when players came out saying that they wanted it more, I gave up at that stage.
"If that is the noise coming out of the dressing room, then no wonder the manager is in trouble and no wonder they are not going to win football matches.
"But that is where Man United are, it is hit and miss. They are going to win matches, but they will lose plenty.
"I am not sure there is a team there. I would love to know what goes on in the training ground.
"Who is pushing each other? Who is helping the younger players? Are the senior players proper?"
Keane won seven Premier League titles during his stint at Old Trafford but he no longer "recognises" the club he once represented despite the optimism that surrounded Sir Jim Ratcliffe and INEOS acquiring control of football operations from the Glazer family earlier this year.
The pundit said: "To be United was always about being good people and characters and people who could play for the club.
"But I don't see that now; I don't recognise the club. A couple of months ago, new people came in, and they thought they would have the answers.
"But they have gone backwards. When we discuss Man United it is more like a business than a football club.
"A football club is about people and good people who turn up and put a shift in.
"What I see at Man United after stepping back a bit I am not sure I am seeing proper footballing people."