Contrary to popular opinion, I have found that most (like 99 percent) business people I have known over the course of my career are exceptionally ethical and moral--they always strive to do the right thing.

While there are always exceptions to every rule, most of the people I have done business with understand that treating people with fairness and honesty is the best way to develop long-lasting and sustainable relationships--which is the bedrock of any successful business.

That's because it's far easier to do business with people you have worked with before. But if you treat people as only part of a transaction--where your only goal is to take advantage of them in some way--you may not care as much about doing things the right way. There is a value in the long-term relationship equity that accrues when you are both dealing fairly but some businesspeople short-circuit that by only looking for short-term gains.

This manifests itself in the kind of behavior where people try to "win" every deal--no matter what kinds of corners they might have to cut, or who they have to manipulate, to get there.

This is why some salespeople get a bad reputation. They think only in terms of winning any one particular deal rather than trying to build a relationship with a customer that might yield return business in the future. The truth is, however, that the best salespeople are exceptionally honest and ethical because they know the value of building a relationship. Their goal is to find the kind of deals where everyone wins.

My parents have gone to the same car salesman for many vehicles and he has probably made thousands in commissions over the years. Why? Because he deals with them directly and fairly, and while he makes a profit, it isn't usurious. 

Obviously, none of us wants to be taken advantage of--or be forced to deal with someone who is unethical in some way. So how to know what signs to watch for?

Based on my experience, there is one simple red flag that every unethical person shares in common: They are the ones who accuse and worry about everyone else being unethical.

Over the course of my career as a leader, I always believed in the axiom "lead with trust." In other words, I started out by trusting everyone until they showed me I couldn't.

But the alarm bells should start going off anytime you meet someone who approaches a relationship with the fear of being taken advantage of by everyone around them. Why? Because that's the first sign that they want to take advantage of you--they just think this way--and will justify it with the idea that they need to do it to you before you do it to them. 

For example, I had a potential client contact me and the first question he asked was: "How do I know you won't screw me?"

I'll admit, I was taken aback. Of course I wasn't out to take advantage of him. And I certainly would do anything he asked to make him feel more comfortable about setting the terms of our working arrangement, as long as it was good for me too.

But I also believe that people with high levels of integrity don't worry about being taken advantage of. So the fact that his primary concern was covering himself was an immediate red flag for me--and I turned down his business.

So if you're wondering if someone you might want to work with is ethical or not, look for the simple sign of whether they're excessively worried about being taken advantage of. Chances are, it means they'll look for a chance to take advantage of you instead.