Here is an excerpt from an article written by Steve Tobak for CBS MoneyWatch, the CBS Interactive Business Network. To check out an abundance of valuable resources and obtain a free subscription to one or more of the website’s newsletters, please click here.

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(MoneyWatch) COMMENTARY Every incompetent employee, lunatic boss and deceitful salesperson is someone’s loving spouse and loyal friend. That does not mean you should hire, work for, trust or do business with them. And yet, we do exactly that, time and again.

Sometimes we get taken; it happens to everyone. But other times we ignore all sorts of red flags. We act against our better judgment.

But why? I mean, why would you or anyone make a ridiculously important decision “against your better judgment?” Because, at that moment, you choose to believe that pigs can fly. That miracles do happen. That universal laws don’t apply to you because you’re special.

You choose hopes and dreams over reason and instinct.

Well, here’s the thing. Pigs can’t fly, miracles don’t happen, the laws of physics do apply to you and hope is always a dumb strategy. Instead of hopes and dreams, learn to listen to your better judgment, trust your instincts, and keep these [three of] seven types of people out of your business.

Trendy self-promoters. There are tons of self-proclaimed entrepreneurs branding themselves as Gen Y consultants, personal branding experts, or both. They’re experts all right — at branding themselves and making money off a trendy stereotype or label.

Salespeople who know their product doesn’t work. Everyone on Wall Street knows that past performance is no indicator of future results and active money management doesn’t outperform the broad market. And yet, money managers make fortunes selling products they know don’t work. How do they sleep at night?

Bottom feeders. When bubbles burst, economies go south and once-thriving industries dry up, enterprising people find other ways to make a living. The worse the economy gets, the more life and career coaches there are. Imagine that. Look, if you need help, find someone who was actually successful at what you want to become.

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Just remember, these are not all bottom feeders you can spot in an instant and steer clear of with ease. Lots of them are highly successful and very wealthy. Some are even senior executives and business leaders. So stay on your toes — it’s a jungle out there.

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To read the complete article, please click here.

Steve Tobak is a consultant and former high-tech senior executive. He’s managing partner of Invisor Consulting, a management consulting and business strategy firm. Contact Steve at the firm, follow him on Facebook, or connect on LinkedIn.