Burger chain Wendy's (NASDAQ:WEN) is hoping to build on the successful viral campaign for its new Pretzel Pub Chicken Sandwich with new webisodes created entirely from fan tweets on Twitter. But while venturing off the well-trod path of in-house advertising can often result in meaningful and memorable ad campaigns, it can also end up an epic fail, and companies would do well to balance the need to be edgy with the real-world requirement of controlling the message.

Crowdsourcing as a means of developing an ad campaign is not new, but it is catching on. Anheuser-Busch InBev ran a crowdsourced ad during the World Series for its new "bowtie" can, Carnival Cruise Lines started running advertisements recently based on comments submitted via social networking sites, and PepsiCo (NASDAQ:PEP) ran two Doritos ads during the Super Bowl this year that came from the chip's fans -- the seventh straight year of chip ads based on crowdsourced content.

Advertising executives are no longer like Mad Men's Don Draper, but are instead guys and gals in T-shirts and slippers, robes and curlers, sitting around the kitchen table dreaming up funny stuff for their favorite products.

Of course, when you invite the great unwashed masses into the executive suite, you sometimes end up with stains on the carpet.

Pepsi's Mountain Dew stumbled when a crowdsourced effort to name a new green-apple-flavored drink -- dubthedew.com -- ended up with "Diabeetus" as the top selection (the site is no longer functional because of this), and Wal-Mart (NYSE:WMT) had a campaign hijacked when some pranksters sent rapper Pitbull to Kodiak, Alaska, after the out-of-the-way discount store received the most Facebook likes during a promotional bid for Listerine that selected the next spot on the rapper's world tour.

Wendy's has thus far avoided a similar fail with its "Pretzel Love Stories" campaign, crowdsourced, like the Doritos ads, from comments ripped from Facebook and Twitter posts. But it's also maintaining control over what actually goes into the final ad. It's when companies relinquish such control to the public that things can go haywire.

Still, like the crowdsource trail blazed by others, even Wendy's pretzel sandwich isn't exactly original. Last year McDonald's came out with the Pretzelnator, a cheeseburger sandwiched between a pretzel bun, and itself a crowdsourced creation released by its German subsidiary.

Sometimes companies invite scorn, such as when Yum! Brands sought to debase a presidential candidates debate by having someone ask the candidates whether they preferred "sausage or pepperoni" in a bid to promote its Pizza Hut chain. Even seemingly well-intentioned efforts can suddenly veer off the intended path, like when McDonald's tried to drum up "love stories" about its chain with a Twitter campaign only to end up with the hashtag taken over by those registering complaints. A similar debacle could easily overrun Wendy's efforts, too.

Should that happen, the chain should do what Wal-Mart and Pitbull did and use the situation to its advantage. The rapper agreed to go to Kodiak, saying he'd travel anywhere for his fans, but he did them one better and invited the pranksters to join him in the Alaskan wilderness.

Most advertisers, Wendy's included, no doubt believe crowdsourcing is a low-cost means of generating publicity for products and companies. When these campaigns are successful, as the pretzel sandwich project is thus far, they can generate more goodwill than any amount of corporate advertising can. But when crowdsourced campaigns go off the rails, it can cost the company more than money to regain its stride.

So far the burger joint has walked that tightrope without incident, but things can get out of hand quickly, and companies can languish in the wake of a failure.