Twitter and Facebook have mostly tamed the problem of trademark infringement and impersonation for brands and celebrities.

On Pinterest, however, it’s all fair game. The swiftly growing image-sharing site has not yet begun to regulate who has the rights to a username.

Take a look around Pinterest to survey the evidence. Pinterest.com/fedex? That’s not the giant shipping company. Pinterest.com/dell? Certainly not Michael Dell’s PC maker. Neither Coke nor McDonald’s has the page you’d expect it to own.

And these are just a few of the boards who’ve lost their brand names on Pinterest. Econsultancy estimates that brandsquatting on Pinterest affects 90 percent of top brands.

It’s not hard to believe that big names and brands are late to the game each time a new social network arises. However, you don’t see domain squatting of this magnitude on Facebook or Twitter, since each network has a policy to bump impersonators.

Could it be that these brands simply haven’t bothered to contact Pinterest to reclaim their names?

Perhaps. But Pinterest’s track record has us thinking otherwise. The company, which has yet to hire a PR person, is nearly impossible to contact. Aside from leading to mass misinformation, this tight-lipped strategy may also be forcing brands to watch as squatters take their names.

A Microsoft employee who asked not to be named told the Daily Dot that repeated attempts to contact Pinterest had been fruitless, and the company was unable to retrieve the Bing or MSN usernames on Pinterest.

Instead, the company has ended up with—let’s be honest here—the ridiculously lame usernames Bing Is For Doing and MSNUS. The latter sounds like a noise a Norwegian makes when sneezing.

If Pinterest continues its unresponsive ways, Microsoft may be stuck with these—or may be forced to take an extremely awkward enforcement action through the courts against the Pinterest users who registered its trademarks as their usernames.

(A Microsoft spokesperson could neither confirm nor deny that Microsoft had attempted to contact Pinterest. To which we can only respond: MSNUS.)

It’s not impossible to get Pinterest’s attention. Just very difficult. After Mitt Romney’s campaign team caught wind of a Mitt Romney Pinterest parody using Romney’s full name, the candidate demanded Pinterest rename the profile.

Pinterest complied, but did not give the original Mitt Romney name to the GOP candidate. Romney’s name now redirects to the profile page of a Pinterest engineer, Alonzo Gomez.

Pinterest Trademark Page states that: “Accounts with usernames, Pin Board names, or any other content that misleads others or violates another’s trademark may be updated, transferred or permanently suspended.”

It then invites affected parties to fill out a trademark complaint form. However, we’ve seen very little evidence to show the company actually reads it.

We know how Pinterest CEO Ben Silbermann will likely explain this: It’s just not a priority compared to making the site “beautiful,” as he told attendees at the recent SXSW Interactive conference.

But there’s nothing beautiful about a site full of deceptive usernames, where people can’t find the brands they want to follow.

Image via Kelly Lieberman