Recent research out of Germany suggests that employees who are forced to smile and take insults from customers at work are more likely to suffer from stress and poor health. That seems like common sense to me. People who are "forced" to do anything typically experience stress, and certainly it's stressful to be insulted by anyone - customer or otherwise.
What surprised me was the proposed solution:
"[The Researcher] found that those able to answer back had a brief increase in heart rate. Those who could not had stress symptoms that lasted much longer....[and] suggested that people who must keep smiling on the job should get regular breaks to let it out."
I'd like to know what the researchers mean by "answering back." According to dictionary.com (see #23) it means:
"answer back, to reply impertinently or rudely."
Maybe I am a dinosaur, but I am from the school of "the customer is always right." When I first entered the workforce some 20 years ago I was taught that while there are plenty of times that the customer is not necessarily "right" in a literal sense, any customer who was prepared to spend money on a product or service offered by my employer deserved to be treated with respect which included listening to him, and working to create a mutually satisfying solution. I would never have dreamed of "answering back." Besides the potential for harming my career, I wouldn't have been proud of myself for sinking to the level of an insulting customer.
Fortunately for me, I had bosses and co-workers who taught me to take pride in being creative in finding ways for both the customer and my company to "win." It became something of a game and was actually rather fun to have a challenging situation come up where I could transform an unhappy customer into a happy one. Often it forged stronger customer relationships in the process. Along the way, I developed communication and business skills that have served me well over the course of my career.
Obviously, the research situation was not real. No matter how bad some workplaces can be, I suspect there are very few where workers are routinely subjected to insults and "forced" to smile. So if you are in a situation where you sometimes are faced with difficult customers, go ahead and smile. Treat it as a chance to use your creativity and innovation to solve a business problem and take pride in producing great results. I guarantee you the high you get from that type of success will far exceed any temporally relief you feel from "answering back."