Apparently, those on this list didn't make it because of an isolated incident .. but rather repeated incidents.
Katherine Heigl: In addition to being a bad tipper, she's also a lousy customer . . . complaining about her food, sending it back multiple times and being extremely demanding. She's worth $25 million.
Sean Penn: He and some friends once ran up a $450 bill at a restaurant in New Orleans, then dashed without leaving SQUAT for the server. He's worth $100 million.
Britney Spears: She once threw change at the feet of a valet attendant and said, "There's your tip." She also left a $26 tip on a $500 bill, which comes to 5%.
And one time at a Vegas restaurant, she made the waiter run across the street and get her Starbucks. She didn't tip him, or even reimburse him for the coffee. And she's got an estimated $200 million in the bank.
Kirsten Dunst: She once left NO TIP on a $223 bill . . . and after she left, the staff said she was whiny and smelled bad. (???) Another time, a restaurant comped her entire meal and she STILL left no tip. Even though she's worth $25 million.
Usher: He's been known to leave AUTOGRAPHED PICTURES of himself instead of cash. He has a net worth of $140 million.
Rachael Ray: Being in the food industry, you'd think she'd be a good tipper. But she regularly tips less than 10%, and has even said on her TV show that 7% is GOOD ENOUGH. Maybe that's why she has $60 million to her name.
Bill Cosby: He's worth $350 million . . . but he once left a $3 on a $350 bill. That's less than 1% tip.
Jeremy Piven: He was banned from all Nobu Matsuhisa restaurants after he took 12 of his friends to one in Aspen in 2007. Even though the place was packed and he didn't have a reservation, they got him a table.
He left the Season One DVD set of "Entourage" as a tip, and on the way out, he told the manager, quote, "Thanks for nothing." Piven has a net worth of $15 million.
Madonna: She's notoriously rude to waiters and often doesn't leave a tip at all. One time she splurged and left an $18 tip on a $400 bill. That's 4.5%. She's worth $650 million. Oh, and she used to be married to fellow bad tipper Sean Penn.
Tiger Woods: While vacationing with a "mystery woman" in Las Vegas one time, Tiger stiffed his waiter . . . so the WOMAN left a tip. Probably out of embarrassment. Tiger has $500 million in the bank.
[ I can personally confirm Vegas table dealers often refer to him as "No Tip Tiger."]