Tesco has been left with a PR headache after it emerged that its own staff have been bad-mouthing customers on social networking site Facebook.
More than 60 Tesco employees have posted insulting remarks about the supermarket's customers on a Facebook group called Tesco employees could rule the world.
The group has now been taken down, but the supermarket has vowed to look into the comments, which poked fun at shoppers using four-letter insults and describing them as smelly, rude, ignorant and stupid.
Tesco has been keen to embrace Facebook as a viral marketing tool, but clearly hasn't learnt from previous high-profile cases that have exposed the PR dangers of social networking sites.
Last year, Virgin Atlantic sacked 13 members of staff for posting comments to a discussion group, which called the company's safety procedures into question and labelled passengers as chavs.
A company cannot blame its employees for wanting to sound off their frustrations, but Tesco is the latest example of why a brand needs to have clear guidelines in place about the use of blogs and social networking sites.
And this also explains why HR departments are gradually introducing clauses to staff contracts that forbid employees from using social media to air their dirty laundry and thereby potentially compromising their employer's reputation.