The Advertising Standards Agency has ruled that a guerrilla social media marketing campaign on Twitter, by confectionary manufacturer Mars, did not breach advertising guidelines.
The ASA received complaints from Twitter users after several high-profile celebrities advertised Snickers bars on their feeds.
Mars said it had paid several celebrities to post a string of four "odd" Tweets that seemed out of character with their personality.
The celebs then posted a fifth Tweet stating "You're not you when you're hungry" - together with a photo of them clutching a Snickers, and the hashtag #spon (which highlights sponsored, or paid-for Tweets).
The ASA complaints referred specifically to posts by Manchester United footballer Rio Ferdinand, and Page 3 glamour girl Jordan (real name Katie Price). Twitter users did not complain about similar advertising Tweets posted by Ian Botham and Cher Lloyd.
Rio's followers began to get suspicious when the bolshy defender - known as being a bit of a 'lad' - started talking about knitting. Jordan's followers were equally stumped when the surgically-enhanced celeb began debating the intricacies of the Eurozone debt crisis.
The ASA investigated the social media marketing campaign to establish whether people reading the celeb's Twitter feeds could have been mislead into thinking the Tweets were "genuine".
The Agency said the four "teaser" Tweets were okay as they did not mention Mars or Snickers - and that the fifth Tweet, containing the "reveal", was clearly an advert as it carried the #spon hashtag.
The watchdog didn't agree with Mars's assertion that only the fifth Tweet truly constituted advertising or marketing: saying the string of Tweets were an "orchestrated advertising campaign". However, it recognised that the Tweets had come in quick succession, and that users were not mislead.
"We considered the combination of those elements was sufficient to make clear the Tweets were advertising,a nd that consumers would then understand each series of Tweets was a marketing communication," the ASA said.
Industry experts say the ruling hasn't shed any light on the use of celebrities on Twitter for marketing purposes - they want better guidance from the ASA to explain what is acceptable and what isn't in social media marketing.
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