Ads are, if nothing else, supposed to differentiate companies, but when it comes to ads that tread on the sensitivities of their intended audiences, mishaps happen and you can differentiate yourself in a bad way. “People are offended by advertising fairly often, in the U.S. and around the world,” says Fred Beard, a University of Oklahoma advertising professor and ad history researcher.

Ads often misfire because of attempts at humor, Beard said. Other times, advertisers try to get attention by skirting the edge of propriety. “Sometimes an ad fails and it winds up offending a lot of people rather than encouraging favorable attitudes and responses,” Beard said.

Here are some of the biggest ad mishaps in memory, including three prominent individual examples and one representative of an entire class, that should cause any advertiser to think twice before signing an insertion order.

AT&T and the Tribute in Lights

An AT&T ad showing a hand holding a smartphone in front New York City’s “Tribute In Lights” 9/11 memorial generated so many critical social media messages that the company pulled it within hours of posting it in September 2013. Nicole Larrauri, managing partner at The EGC Group advertising agency in Melville, New York, said the advertiser simply failed to realize that people didn’t want to talk about a disaster with a phone company. “That’s a fail on a lot of levels,” she said.

Photoshopped Celebrity Smooches

Benetton Colors has been known for edgy ads for decades. But in 2011 when the Italian fashion company ran a series of digitally altered images showing various world leaders nuzzling political archrivals, it crossed the line. Denunciations rained in from the White House on down. And Benetton pulled one ad, featuring a doctored photo of the Pope kissing an Islamic imam, after the Vatican threatened legal action.

Just For Feet

During the 1999 Super Bowl shoe retailer Just For Feet spent more than $7 million to air a 30-second commercial that the company hoped would lead to a groundswell of public goodwill. Instead the ad, which depicted a group of men drugging a runner and knotting Nike sneakers onto his feet, created so much controversy that the retailer sued its advertising agency for $10 million.

Just For Feet-style stumbles can be avoided by testing ad copy with consumers in advance, Beard says. Knowing your customers also helps. Larrauri notes that a simple Twitter search can tell an advertiser what customers are saying and, hopefully, avoid adding to the roster of the worst advertising mistakes. “There are so many tools that are free for a small business,” she said. “You just have to use them.”

Uber and Getaround

So how bad is a recent pair of Facebook promos from ride-sharing rivals Uber and Getaround that used virtually identical photographs — even employing the same female model — to plug their offerings? Until Burger King starts featuring Ronald McDonald in its campaigns, this ad misstep has to be one of the most egregious around.

If you want to avoid adding to the roster of chuckleheaded ads, a few rules can help. For instance, Noelle Federico, chief marketing officer of Nashville stock photography company, says Uber and Lyft could have kept from accidentally imitating each other by purchasing all rights to the image. “It’s a little more expensive than purchasing the photo for one use,” she said. “But that takes the image off the market.”

Calvin Klein and Brooke Shields

It didn’t take as much to shock in 1980, when a teenage Brooke Shields famously declared nothing came between her and her Calvin Kleins. CBS network refused to air the ad, but it ran for years on other networks. The campaign affected more than jeans sales, Beard said, by showing the way for countless envelope-pushing ads since. “Calvin Klein is considered by some to be the modern inventor of shock advertising,” he said.

Captain Colortyme

“The worst campaigns that I see are local ads, TV or print, where the owners think they are experts, and ad sales people feed their egos by encouraging them to be the star of the commercial,” said Matt Kelton, a former franchisee of the rent-to-own company Colortyme. “It happened to me.”

Captain Colortyme was an animated superhero character the company created in the 1980s to give it a distinct image. That was fine, but when Kelton dressed up as the Captain and appeared in a hokey commercial on a local Texas TV station, that was not. “I’m embarrassed to admit it,” said Kelton, now chief operating officer of Showhomes. Today, Kelton regards his escapade as exemplary of the countless similarly silly ads on local media.

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