With Halloween upon us, we’re sharing five of the biggest marketing horror stories of all time. See what you can learn from mega-mistakes made by major marketing powerhouses.

LifeLock: The marketing trick that became a treat for thieves.

LifeLock is a well known identity theft prevention firm that alerts clients when it detects fake applications for credit cards, mortgages and car loans.

The firm was so confident of its service that several years ago it ran an ad that showed the social security number of CEO Todd Davis on television screens across America.

Needless to say, a number of identity thieves took the bait, used the information to apply for loans and weren’t detected by the LifeLock system. The only way Davis found out about the problem is when collection agencies started calling him to pay up on the fraudulent loans.

The lesson: A sound marketing campaign is always backed-up by an air-tight value proposition. Never say anything in an ad that hasn’t been thoroughly tested. Don’t say it if your company can’t pay off on it.

Blockbuster gets busted.

Think about this marketing nightmare while you watch horror movies from streaming video services this Halloween.

Back in 2004, when this video rental giant was beginning to realize that the writing was on the wall, the company knew something needed to be done to stem the tide of customer losses, so it eliminated late fees. The problem: Instead of late fees, Blockbuster charged customers the purchase price of the movies they borrowed seven days after the due date without their permission.

Blockbuster was fined $630,000 by the government for this fraudulent practice and it was forced to refund customers the money charged to purchase the movies.

This issue increased customer dissatisfaction with Blockbuster and was a big contributing factor to the compqny going out of business a few years later.

The lesson: If your firm undertakes a campaign about fees (a relatively common practice in the financial and professional services industries), make sure it is foolproof. There are more opportunities than ever for clients to publicly complain and share information about higher or hidden replacement fees.

The JP Morgan chat that got “trolled”.

In 2013, the investment bank decided to hold a Twitter chat as part of its social media #AskJPM campaign. This was at a time when financial firms were still very unpopular because of the 2008 market crash and its aftermath.

Unfortunately, JP Morgan didn’t get many substantive questions for its bankers to answer. Instead, it received a lot of harsh comments from online trolls — people out to harass the firm. This forced them to very publicly cancel the chat.

The lesson: Use social media as a testing ground for your marketing efforts. Ask your followers if they’d find a potential campaign or effort — such as a Twitter chat — helpful. It will help you determine if you’re heading in the right direction and could prevent an embarrassing incident.

Walmart Halloween costumes become a bad dream.

Two years ago, Walmart labeled a series of costumes on its website as “Fat Girl Costumes”. Though the label was relatively small, the firm faced a huge public backlash when screen images were shared in social media. People called out the superstore for their less-than-sensitive language.

To their credit, Walmart quickly removed the listing from their website. However, they did not scrub the site for other similar terminology. People on social media continued to call them out for negative words on other parts of their site.

The lesson: It’s an acknowledged best practice for firms to respond to social media concerns immediately. However, make sure any response is a comprehensive one that looks into the possibility that you could have other similar issues lurking on a website or in other marketing materials.

Tip: An agency experienced in web content development can review your website to look for terms or phrases that could be interpreted by prospects or clients in unintended ways.

Barclays and Dan, the hypothetical client that clients disliked.

Back in 2013, this big financial firm tried putting on a more human “mask” by creating Dan, a character that was supposed to represent the typical financial consumer. While the concept of Dan was well-intended — to teach financial literacy — the campaign flamed out.

Consumers found Dan, and the financial scenarios Barclays placed him into, simplistic and condescending. They felt the firm was underestimating their intelligence and insulting them. Barclays quickly shut down the campaign.

The lesson: Never underestimate the sophistication of your consumer base. Nothing will turn them off faster and send them running to your competitors. Develop clear and detailed client personas so you always understand who you’re communicating with and how to do so effectively.

Want fewer tricks and more treats in your marketing efforts? Carpenter Group has helped countless firms in the financial and professional services industries avoid surprises and generate results for more than 35 years.