telemarketersMembers of Congress, lobbyists, and car salesmen edged out telemarketers as having the worst reputations for honesty and ethical standards, according to a Gallup poll taken at the end of 2011. Other professions that ranked low on the trustworthiness scale include business executives, stock brokers and real estate agents.

What makes these professions so maligned by the average American? Not all people in these industries are cheaters, liars or flat-out crooks. But while there are bad seeds in every industry, those seeds really bloom in these professions. And it all boils down to bad incentives -- incentives riddled with conflicts of interest that allow (encourage, even) people to rationalize bad, unethical behavior.

Here's a look at how misaligned incentives affect the behavior of professionals in five fields Americans distrust.

Motley Fool contributor M. Joy Hayes, Ph.D., is the Principal at ethics consulting firm Courageous Ethics. She owns shares of AT&T. Follow JoyofEthics on Twitter. The Motley Fool owns shares of Lockheed Martin and Apple. Motley Fool newsletter services have recommended buying shares of and creating a bull call spread position in Apple.

Increase your money and finance knowledge from home

Banking Services 101

Understand your bank's services, and how to get the most from them

View Course »

How to Buy a Car

How to get the best deal and buy a car with confidence.

View Course »