Stupidity is contagious. It gets us all from time to time. Even respectable companies can catch it. As I do every week, let's take a look at five dumb financial events this week that may make your head spin.

1. Mother jokes about Ma Bell
As if network notoriety and eradication of unlimited data plans weren't bad enough, AT&T (NYSE: T) hurt Apple (Nasdaq: AAPL) again in a data breach that exposed 114,000 of Apple's iPad owners on AT&T's 3G data plan.

Only email addresses and iPad identification numbers were divulged, but the FBI is now investigating the matter, since some of those exposed happen to be high-ranking government officials. This is also a telemarketer's dream list of likely well-to-do early adopters, so I'm sure that the spam filling these inboxes is going to be substantial.

I don't think even another wave of Owen Wilson ads can spare AT&T's reputation among Apple fans.

2. This week in bad math
Sprint Nextel (NYSE: S) didn't leak the names of its wireless customers, but it also stumbled this week when it spoke too soon.

The carrier turned heads on Monday when it said that the HTC's EVO 4G, the country's first 4G smartphone, rang up three times as many sales on its launch day than the Instinct or Pre did combined during their first three days on the market.

"We inadvertently erred in the comparison," Sprint sheepishly confessed a day later. It had overstated its performance by two-thirds, since the EVO's launch day simply matched what the Instinct and Pre sold combined during their first three days.

That's still an impressive performance, and it bodes well for the latest phone based on Google's (Nasdaq: GOOG) fast-growing Android platform. However, the blunder will cost Sprint in the form of skepticism the next time it toots its horn.

3. That's why they call it crude
BP (NYSE: BP) has problems cleaning up its Gulf of Mexico spill, but it's also stumbling as it tries to clean up its reputation.

CNNMoney reports that BP is advertising on all of the leading search engines, bidding up spots for keywords including "oil spill" and "oil spill claims."

In theory, this is a great idea. BP's reputation is getting as murky as patches of the gulf. Making sure that it's the top result for search queries about the ecological catastrophe can help it shape public opinion.

However, at a time when BP's cleanup efforts and even its dividend policy are coming under fire, it can't help for search-engine users to see "sponsored link" tags attached to BP ads. The television, print, and online marketing in pursuit of brand restoration may be necessary, but it sends the wrong message in terms of budget allocation.

4. Mr. Softy's cash flow  
Money is moving in different directions as Microsoft (Nasdaq: MSFT) finally launched a free Web-based version of its Office productivity suite and is axing the Bing cash-back feature on sponsored deals.

They're both bad moves for the world's largest software company.

One can argue that Microsoft doesn't have much of a choice in offering up scaled-back versions of Word, Excel, PowerPoint, and OneNote on the cloud for free. The company has to compete against Open Office and Google Docs. However, this isn't likely to drum up sales of the commercial software. Giving something away, with hopes of hooking users into buying to the premium platform, won't work too well when competitors' full-scale products are likely to remain as ad-supported freebies.

Microsoft was offering Bing visitors a piece of the action on any purchases they made from its shopping portal. If a website can attract shoppers, it's also likely to attract a wide variety of advertisers that want to reach an audience predisposed toward making online transactions. What happens now? Bing regulars who used the cash-back feature are unlikely to return, because they'll be reminded of the money that they're now leaving on the table. They'll flock to smaller loyalty-shopping sites. This is a rare misstep for Bing.

5. Sacked for a loss
Disney (NYSE: DIS) is closing most of its ESPN Zone themed restaurants and sports bars.

This may not seem like a bad idea. The ESPN brand certainly doesn't need any ambassadorial assists, and most of its high-traffic locations were sitting on costly real estate. However, it's just another sign that the family-entertainment giant is sputtering in location-based entertainment and retail.

Just as it has sold off, bought back, and scaled back its Disney Store empire, Disney has also shuttered branded high-tech arcades, kid-play centers, and themed eateries early in their infancies. Disney's cruise ships and timeshare resorts appear to be holding up well, but it has a surprisingly spotty track record beyond that outside of its theme parks.

Which of these five moves do you think is the dumbest? Share your thoughts in the comments box below.

Walt Disney, Microsoft, and Sprint Nextel are Motley Fool Inside Value recommendations. Google is a Motley Fool Rule Breakers pick. Apple and Walt Disney are Motley Fool Stock Advisor selections. Motley Fool Options has recommended a diagonal call position on Microsoft. Try any of our Foolish newsletter services free for 30 days.

Longtime Fool contributor Rick Munarriz is a fan of dumb and smart business moves, because investors can learn plenty from both. He owns shares of Disney and is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.