Both men made their fortunes in sportswear retailing with Whelan taking over Wigan in 1995 when they were a lower league club and Ashley taking over Newcastle in 2007.
"When I first went there just after Mike Ashley had bought it he turned up in the boardroom in a pair of jeans, a pair of trainers and a replica shirt. Immediately he did that, the club's gone," Whelan told Thursday's Sun newspaper.
"You don't do things like that in football. He's got no class whatsoever. He's representing Newcastle United who were such a proud club.
"I immediately knew the supporters may want to have a pint with him on the terraces but basically he was not Newcastle through and through. The Newcastle fans know that.
"You can't get a Tottenham fan buying Newcastle and letting people thinks he supports them.
"It's not right, there's no pride left in the club."
Ashley was initially welcomed at Newcastle, especially after bringing back Kevin Keegan as manager, but after Keegan's departure earlier this season his popularity has plummeted with the team's league position.
Now third-last in the standings Newcastle are in real danger of relegation.
"I think he's got what he deserved. You don't go into a football club as big and proud as that and lower the standards," Whelan said.
Whelan sold his JJB Sports business in 2007 but has since bought back the group's fitness clubs. He has renamed them DW Sports Fitness and as a result will change the name of the club's 10-year-old JJB Stadium to the DW Stadium as of next season.
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