Would you buy a pair of shoes because someone on Instagram said they were great? Or choose a new phone based on the recommendation of a top YouTuber?If so, you are proof of the effectiveness of influencer marketing. On this week’s Tech Tent podcast, we explore the phenomenon.Influencers – social media stars with big followings – have been under the spotlight this week for two reasons.First, the UK’s Competition and Markets Authority revealed that 16 influencers had promised to be far more transparent when paid to promote a product.The regulator has taken a dim view of celebrities posting images of themselves with an “awesome” product, without mentioning that the “fabulous” company behind it has paid them a tidy sum to be quite so enthusiastic.They will now be encouraged to use hashtags such as #ad, #sponsored or #freebie to give their fans a clearer picture of what’s going on, otherwise they could land up in court.But this week also saw the release of two documentaries about the disastrous Fyre Festival, which appeared to be the apotheosis of influencer marketing. It showed the power of the influencers. Kendall Jenner was reportedly paid $250,000 (£190,000) for one Instagram post promoting tickets that rapidly sold out.It raised questions about the ethics of this form of marketing. The supermodels and other celebrities were happy enough to take money from the Fyre Festival organisers. But when the whole event turned into a fiasco, they faced no consequences for taking part in a very dishonest marketing campaign.“We can see how precarious that is in terms of the legitimacy of those campaigns,” says Dr Mariann Hardey, associate professor in marketing at Durham University.She is a sceptic about influencer marketing and tells us it is really just another form of that age-old advertising technique, the celebrity endorsement.“I don’t think this is the holy grail. Influencers simply amplify traditional marketing methods and strategies,” she says.