There's an old adage that the customer is always right. But that's all it is: a saying.

The truth is that the customer isn't always right. Running my own e-commerce company has taught me that it's especially important to balance the needs of your customers with those of your employees.

Many companies live in fear that customers will become angry about something, and then take their business elsewhere. In the age of social media, they might tell 1,000 of their closest friends not to support your business.

Remember when Dave Carroll flew with United Airlines and had his guitar broken? A yearlong customer service battle ensued over the $1,200 in damages. He wrote a song about the ordeal, which went viral on YouTube with over 16 million views. The fight reportedly cost United $180 million, which was ten percent of their Share value.

Carroll's complaint was warranted. Not all customer service inquiries, however, are created equally. Some customers know you're so eager to please that you're willing to do almost anything to keep them around. Some of the more unscrupulous of customers will even take advantage of you.

There are some times that the customers really are wrong. Here are three of them:

1. When It Makes Your Employees Unhappy

There's no reason for one of your staff members to tolerate abuse from anyone, especially a customer. Sometimes, customers don't see eye-to-eye with a staff member. They ask to speak with a manager. They want the staff person reprimanded, or in some kind of trouble.

If you listen to both sides and decide that your employee is right, then you need to side with your staff member. They aren't your servants. Treat them well, and be loyal to your staff. They will be happy working with you, and act loyal in return.

2. When You're Dealing With Bad Customers

If you're telling a demanding customer that he or she is right, aren't you essentially rewarding bad behavior? Don't give bad customers--ones who are giving your staff unwarranted difficulty--more attention than they deserve.

3. When It's More Trouble Than It's Worth

Every customer isn't valuable--there are some that we can certainly live without. Like the customers who are headaches for your company, for example. The ones who won't lead to any more referrals or sales, and who give your staff trouble time and again.

They simply aren't worth the stress. After all, time is money. Write them off, and focus your energy on the customers that deserve your services.

There are, of course, times when the customer is right. Times when you make mistakes. Times when you need to compensate them for a poor experience, or some other reason. But customers are people too, and they can be wrong.

How are you treating your customers?