Management plays an important filter because investors do not run businesses, but the original owners continue to run the show

Buffett speaks
I am investing in a business, not in a stock
Buffett is not just a successful stock picker but rather a more successful business buyer. And his success has more to do with the wonderful businesses that he owns rather than their stock price movement. Says Charlie Munger, 'We've really made the money out of high-quality businesses... Over the long term, it's hard for a stock to earn a much better return than the business which underlies it earns. If the business earns 6 per cent on capital over 40 years and you hold it for those 40 years, you're not going to make much different than a 6 per cent return, even if you originally buy it at a huge discount. Conversely, if a business earns 18 per cent on capital over 20 or 30 years, even if you pay an expensive-looking price, you'll end up with one hell of a result.

A lesson on elementary, worldly wisdom as it relates to investment management and business, Charlie Munger

Well, what do you look for in a girl? Seriously, you look for the logical things-passion, an interest in running the business, honesty. Such as, do they love the business, or do they love the money? This is the first filter. Mrs. B ran Nebraska Furniture Mart until she died at the age of 103-that's passion.
Tuck School of Business trip to Omaha, 2005

We got a book from an investment bank from someone who bought a business a few years ago [and now wanted to sell it]. The business was a piece of meat to them. What are the odds that they didn't doctor the books? 
Annual Meeting notes, 2003

Passion is the number one thing that I look for in a manager. IQ is not really that important. I'd say intelligence, energy, integrity. If you don't have the last one, the first two will kill you. All you have is a crook who works hard.

The primary test of managerial economic performance is the achievement of a high earnings rate on equity capital employed (without undue leverage, accounting gimmickry) and not the achievement of consistent gains in EPS.
Annual Letter, 1979