This post was originally published on LinkedIn.

Some executives don’t seem to care what their employees do to close a sale. Customers vote with their wallets, so buyers must have liked what they saw, right?

Would those executives feel the same if they knew their salespeople over-promised and used half-truths to hook customers? Would they be outraged if an elderly shopper was bullied into buying a warranty he didn’t need?

They should be. Those salespeople might have raked in a few extra dollars of revenue, but their selfish actions created unhappy customers who won’t hesitate to warn all their friends about their bad experience.

These angry customers, or detractors, can kill a company. If they can switch to the competition, they will. If they can’t—because, for example, they’re locked into long-term contracts or long-lived products like cars—they will bring every single request and complaint, no matter how minor, to customer service reps, driving up costs and demoralizing employees with their frustration and bitterness. They’ll badmouth the company or its products to anyone who will listen.

Often, it’s a company’s customer-unfriendly policies that create detractors. But sometimes it’s the sales reps themselves. They aren’t straight with people. They persuade customers to buy products or options or services that the customers don’t really want. The buyer goes home feeling taken advantage of—and angry.

If you were running this company, wouldn’t you want to know which reps were creating promoters and which were creating the most detractors? Most companies have no clue. They don’t even know who the detractors are among their customers, or how many detractors they have, or whether the number has been increasing or decreasing. So they can’t do anything about the problem salespeople.

But some companies do know. Net Promoter System® users, for example, regularly ask customers how likely they are to recommend the company to friends and family. These short, frequent surveys identify detractors right away. Managers can then call detractors to find out why they feel as they do. The survey data and comments allow the company to identify troublesome branches, products or policies—and, yes, the individual sales reps who are turning customers off.

And then the companies can take remedial action. In the case of salespeople, that might mean better training, a different incentive plan, more careful hiring or, in some cases, dismissal.

If you run a business, you need to know which salespeople are creating those detractors. They may be making lots of sales—but they are destroying your growth and your reputation.