AOL, the beleaguered online service, is probably glad that the month of June is over....

Besides aggravating many long-time customers by inserting ads into their emails, AOL execs found themselves in the spotlight for shooting themselves in the foot—again. In the now-famous “I want to cancel my account” episode, AOL subscriber, Vincent Ferrari, battled mightily with a service rep to shut down his account.

Ferrari recorded his tussle, which circulated widely, and it landed him an interview with Matt Lauer on Today. AOL execs apologized to Ferrari, discussed the story with the media, and fired the customer service rep.

AOL’s self-inflicted wound reveals the perils of unleashing an aggressive sales strategy using customer service staff. Granted, most customers expect to hear some sales pitch when they talk to a service rep. But tenacious efforts to sell something to a customer seeking service violate a simple rule of marketing: customer service is a better marketing opportunity than a sales tool.

Customer support, of course, is an enormous expense for most businesses, and it’s tough to ignore the sales opportunity that presents itself in any interaction with a customer. But why not take advantage of the power of customer goodwill and word-of-mouth marketing by offering error-free service, rather than an unwanted sales spiel?

By focusing on service, and its marketing benefits, a business may not wind up on YouTube, Digg, or Today. But that could be the ideal outcome.