The Insider.com

Celebrity shoe man Steve Madden pretty much confirmed everyone's suspicion that Ashley and Mary-Kate Olsen aren't the most ideal co-workers, when he candidly called them a "pain in the ass" to work with at last night's star-studded Italian sneaker brand Superga's SoHo party.

• May 31, 2012Kim Kardashian's 'Wet & Wild' New Photos
• May 31, 2012VIP Party Pass: The Nylon Mag Music Issue Party
• May 31, 2012Driver Drops Assault Charge Against Fox
• May 31, 2012Snooki Tweets High School Photos
• May 31, 2012Kristen Bell's CMT Wardrobe Dilemma
• May 30, 2012January Jones' Scariest Hollywood Moment

Related: Mary-Kate's Beau Old Enough to Be Her Dad?

"They are difficult. They are exacting," he told Fashionista.com, after calling their collaboration experience on both the twins' Elizabeth and James shoe line and now the Superga sneakers "painful." "They are a pain in the ass. But they're very good though."

"They're very demanding, they're very tough," he continued. "You know, just tough, tough. They want what they want. And so we worked hard to get that done."

The Olsen Twins' Epic Tyra Banks Diss

But give the twins a break -- you don't get a billion dollar fashion empire and fashion icon status at just 25 years old without having some very strict standards to say the least.

… and I'm sure constantly keeping the weight off makes them a bit cranky.