1. Donald Sterling (Clippers)
In 30 years with him as the owner, Donald Sterling's Clippers have had a winning season all of twice. Sterling’s poor ownership has turned the Clippers into the punchline of any NBA joke (not involving LeBron James). Sterling is notoriously frugal when it comes to his players and front office, rarely giving out any large contracts - and in the rare instances that he did, he gave those contracts to the wrong players.
But simply owning a bad team isn’t quite enough to get you on this list. Sterling has made many, many more missteps that demonstrated how he should have no business owning a pro sports team. He's been sued several times for sexual harassment and racial discrimination, including by former GM Elgin Baylor.
In Baylor’s suit, Sterling’s numermous horrible comments and business practices came to light, such as his telling Baylor he wanted to fill his team with “poor black boys from the South and a white head coach.” Which is nothing compared to housing discrimination claims (Sterling made his money as a slumlord) in which Sterling allegedly said “black tenants smell and attract vermin,” and "Hispanics smoke, drink and just hang around the building."
When former Clippers coach Kim Hughes needed surgery for prostate cancer, Sterling refused to pay for an out-of-network procedure, leading Yahoo! Sports' Kelly Dwyer to brand him the "worst person in the world." The bill of $70,000 was eventually paid by current and former Clippers players Corey Maggette, Marko Jaric, Chris Kaman and Elton Brand.
To top it all off, Sterling has even been heard at Clippers games heckling his own players.