It’s happened to me, and maybe it’s happened to you. You’re so keen to make a sale that you overrule the warning signs your gut is giving you.

I recently fielded a phone call from a distressed woman who needed help planning a honeymoon, but no other travel agents would speak with her. My first thought was, “Are you that much of a pain in the neck that no one will talk with you?” And as fast as that thought entered my head, it fled. Why didn’t I listen to myself?

After a week of working with this woman, spending countless hours of revisions on a honeymoon for no ultimate payoff, I realized how much smarter the other travel agents were for bypassing this woman as a client. Why did I ignore my gut and work a week for free on this noncustomer?

Well, I thought I could make a sale where others couldn’t, frankly. So keen to make a sale that I forgot to consider whether I even wanted this woman as a client.

A local hardware store manager told me recently that she had spent a good hour explaining the workings of a high-end barbeque grill and smoker to a browsing, interested customer.

Answered all his questions. Gave him recipes. Detailed the differences between this model and that model. He said he would think about it while he was out of town for a couple of days.

He was a phony. He actually spent the next day shopping competitors. He called the store manager, and the first words out of his mouth were, "The store down the street is willing to give me this and that. What are you going to give me?"

The manager related to me that then and there she knew she should have told him to take the offer from the other store. But no, keen to make a sale, she added this perk and that one.

He ended up buying the product online from a competitor, not at the store where he had consumed so much energy. And yet, when he decided he didn’t like the product after all, he called this manager—from the store where he did not buy the item — to see if they would return it for him to save him shipping charges.

The manager said to me, "I knew he was going to be trouble as soon as he asked what we were going to do for him. Why did I go out of my way to help this noncustomer?"

Why indeed.

Maybe it’s the competitive spirit inherent in many entrepreneurs. That sense of accomplishment and fulfillment when you ace a sale, finalize a contract, surpass your sales goals.

Maybe it’s ego. That sense that I can accomplish what others can’t. That’s dangerous ground to be on as it can cloud your judgment, as it did me.

But when you’re keen to make a sale at any price, I’ve learned that “any price” can be too much to pay.