Disgruntled fliers taking to Twitter to vent their grievances about airlines has become commonplace. But a consumer turning one of those 140-character complaint into an ad? That's something new -- and marketers should have a plan to navigate this new potential route for consumer complaints to go viral.

British Airways had to learn the lesson the hard way. A passenger this week, dissatissfied with the carrier's inattention to his tweets about his lost luggage, decided to promote those tweets in Twitter's self-serve ad tool to voice his disdain more widely.

The user, Hasan Syed, promoted the tweet in New York City and in the U.K. on Monday night, according to Mashable.

I refuse to stop running Twitter Ads until @British_Airways finds the lost luggage— � (@HVSVN) September 3, 2013

The British Airways Twitter account - which states in its profile that it's manned during weekday business hours only -- eventually did respond, but only to request a reference number. And that only enflamed Mr. Syed more.

@HVSVN We can't DM you as you aren't following us. If you'd like assistance we will need your baggage reference.— British Airways (@British_Airways) September 3, 2013

Soon his complaints were noticed by media outlets, surely part of his motivation in spending money on Twitter ads. Mr. Syed hasn't disclosed how much he spent on his Twitter campaign. But the social network's ad engine relies on a combination of bid price and relevance to determine how often the ad will be shown, so a person with 30 followers mainly consisting of friends and family who rarely sign in would need to pay more for the same distribution than someone with thousands of followers who regularly retweet and favorite his tweets. (Mr. Syed has 838 followers and has tweeted 371 times as of this writing.)

Ultimately, British Airways apologized to Mr. Syed and told PR Week that it had his luggage and was working to return it to him, but that was after a routine dust-up had turned into a well-publicized corporate gaffe.

Brand Response
Whether Mr. Syed's novel use of Twitter sets a precedent remains to be seen. But brands beware: there's not much companies can do to stop determined haters from buying Twitter ads. While Twitter's rules prohibit ads that make false statements, and those ads can be flagged for removal, it would be difficult to prove that a customer issue with lost luggage was false, for example.

Brands do, however, have recourse of making competitive bids on relevant keywords, whether it's with disgruntled customers or competitors looking to conduct a Twitter hijacking of a term linked to their rival. There's no guarantee that that will serve to drown out the other voice altogether -- especially if it's one that's relevant, or highly engaged with by other Twitter users. But someone who bids on a keyword alone, and whom Twitter's ad engine ascribes some degree of relevance to, is bound to get distribution, according to a Twitter spokesman.

If other people do follow Mr. Syed's lead, airlines are a logical target due to the social-media wrath they regularly incite based on customer service, according to Ian Schafer, CEO of Deep Focus. He suggested British Airways might have placated Mr. Syed by offering him a travel voucher worth the amount he spent on his promoted tweets, conveying that "this is not something we intend to do in the long term, but this individual has a good point," he said.

Whether it's a promoted tweet or an organic one, marketers should ascertain first whether the person complaining is a legitimately dissatisfied customer or a troll who can't be mollified.

"One thing the internet's taught us is that there are some people who will never be happy," Mr. Schafer said. He added that he used to tweet often about New Jersey Transit, but the fact that the account was responsive and usually gave an explanation for why a train was delayed or why it was stalling in between stations caused him to stop complaining.

Gauging whether the person doing the complaining has any influence is also an important precursor to a brand plunging into a public Twitter exchange, according to Traction CEO Adam Kleinberg. "With someone with six followers who's on Twitter and who makes a nasty tweet, it's completely irrelevant," he said.

And even when they do have a substantial following, it might not be worth fanning the flames and drawing more attention to an issue that people are unlikely to pick up on, he said. Traction client Nomsi, a recently launched juice brand, was mentioned in a tweet by someone with a million followers, who said that her first encounter with the brand was almost getting run over on the sidewalk by a bicycle that was involved with a guerrilla marketing effort. Instead of tweeting back to her, Nomsi sent her an apologetic email and then a six-pack of the drink.

"You can't respond to everything," Mr. Kleinberg said. "Why call more attention to it?"