According to the Federal Trace Commission, transparency is a must when it comes to sponsored Tweets and celebrity endorsement. But the commission feigned to take action when Tennis star Serena Williams twice tweeted remarks lauding Nabisco's 100 Calorie Packs, omitting disclosure in the second.

The FTC recently updated their celebrity endorsement and transparency guidelines to include Web and social media. The commission claims it has and will never punish an individual for failing to disclaim sponsorship, but hinted that they would in some cases take action against companies.

Then recently Williams posted the following remarks to her Twitter feed, sequentially.

First: "Venus and I are shooting a campaign for Nabisco 100 Calorie Packs!! They r soooo amazingly good we keep eating them. But we arnt worried..."

Second: "... We r not worried about staying fit because the Nabisco Calorie Packs are only 100 calories!!!! U guys must run out and try them!!!"

In August of last year, Serena and sister Venus joined brothers Eli Manning and Peyton Manning as celebrity brand ambassadors for Nabisco. Ever since they've appeared in various ads, most prominently the Oreo Double Stuf Racing League campaign. For some of Williams' 1 million plus followers, the sponsorship may have been obvious. But there's no guarantee, a fact the FTC was remiss to admit.

Richard Cleland, Assistant Director, of the FTC's Division of Advertising Practices said of the situation: "Although we do not generally comment publicly about ongoing advertising campaigns, it seems pretty clear that Serena Williams' tweet about Nabisco Calorie Pack is sponsored advertising. (She says that she is shooting a campaign for Nabisco). When it is clear from the context of a communication that the celebrity is being paid, an additional disclosure is not required."

Does this mean that an endorser can supply just one disclosure, thereby opening the door for undisclosed Tweets (tangentially, this would seem to apply to blog posts, comments made in public, et al)? The FTC did not clarify. If so, such endorsements will be at risk of falling down the slippery slope. Moreover it begs the question: what good is a set of guidelines that fails to draw a hard line on what is essentially a black and white issue? Either you disclose, or you don't.

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