Two tales of employee behavior made the rounds at roughly the same time this week.

The first features 18-year-old Dunkin’ Donuts employee Abid Adar who is being widely heralded as the face of a company that takes employee training and corporate social responsibility seriously. By virtue of the fact that he was working the counter when customer Taylor Chapman entered the Florida shop, Adar has been catapulted to social media (and now mainstream media) fame.

Chapman had visited the Dunkin’ Donuts the night before, when she said she didn’t get a receipt. Dunkin’ Donuts offers your order free if you don’t get a receipt, so she came back, armed with her smartphone, and recorded the exchange while demanding free product. She clearly expected an argument, and she was prepared with a supply of profanities to do battle on camera. What she got was a polite, respectful employee whose behavior was exemplary. Chapman posted the video anyway; on YouTube, it has nearly 700,000 views. Watch at your own risk; Chapman lets the vulgarities fly with reckless abandon.

The second tale comes from Wendy’s, a Dunkin’ Donuts competitor in the fast food space. Neither the employee nor his location are named, yet the photo was getting a lot of attention on Reddit, where it was posted with the title, “I was going to buy a frosty from Wendy’s until I saw the employee do this.” The image has made the rounds since then, with the mainstream press picking it up and the NY Daily News reporting a Wendy’s spokesman confirmed the employee “was no longer with the restaurant.”

Taken separately, these tales can inspire observations about the impact of social media. In the Wendy’s case—disturbingly similar to the recent image of a Taco Bell employee licking taco shells—the distribution of the image through social networks can influence consumer behavior. When a video surfaced in 2009 of Domino’s pizza employees doing disgusting things to food destined for customers, the company’s chief financial officer had to report the resulting lost sales in a quarterly earnings call.

Conversely, Dunkin’ Donuts has been basking in the glow of universal praise for Adar’s reaction to a customer’s onslaught. PC World, for example, asks, “Why did Dunkin’ Donuts survive this experience when so many others have failed?” and lists what companies can learn from Dunkin’ Donuts (including the importance of training, the assumption that everything is being recorded, and a focus on resolving problems quickly).

Of course, the same advice will undoubtedly be offered to Wendy’s. Some social media blogger somewhere—and probably more than one—will offer advice to Wendy’s about how to prevent a recurrence of this episode.

And then there’s The Inquisitr, which concludes its coverage of the Wendy’s photo entreating you not to let the Wendy’s and Taco Bell incidents sour you on fast food. “After all, you can always eat at Dunkin’ Donuts where the employees are well-behaved, well-mannered, and display an uncanny ability to take racist abuse.”

But there is a larger lesson that emerges when these two stories are considered as a matched pair. Wendy’s undoubtedly employs employees who would never behave as the employee in the photo did, and would behave with the same dignity and poise that Adar demonstrated at Dunkin’ Donuts. By the same token, somewhere there’s a Dunkin’ Donuts employee ready to embarrass the company.

Fast food companies employ tens of thousands of young, inexperienced, low-paid workers who won’t always be on their best behavior at work, whose idea of what’s funny isn’t necessarily the same as yours or mine. This truth extends into the broader retail world. With every customer equipped with a video camera, the best and worst behavior of your front-line staff will inevitably be put on display.

The best defense against these stories that will continue to get traction on social networks is to know they’re coming and there’s nothing you can do to stop them. Training is vital, of course, but many employees whose misbehavior has brought grief to a company completed well-planned, engaging and thorough training programs. Training will minimize such problems but it’s a pipe dream to believe there’s anything that can prevent it altogether.

Knowing such incidents will occur should lead you to develop a response you can deliver with confidence. It’s a much better approach than expressing shock and surprise when teenagers act like teenagers.