The BBC's technology correspondent Rory Cellan-Jones said that many Facebook account holders who 'like' products have actually lied about their personal details.
Security experts even warn that profiles are being created by hackers to spread spam on the social network, although Facebook denies this.
'Likes' are highly valued by brands because it allows them to post content directly onto the Facebook user's news feed, thus promoting it to their network of 'friends'.
The BBC spoke to Michael Tinmouth, a social media marketing consultant, who ran a number of Facebook ad campaigns for small businesses, but soon went cold on the initiative.
He said his clients were at first pleased by the number of 'likes', but become concerned after analysing who was actually clicking on their adverts.
It was found that many 'likes' were coming from countries such as Egypt and the Philippines, and many derived from profiles that had 'liked' thousands of other pages.
"They were 13 to 17 years old, the profile names were highly suspicious, and when we dug deeper a number of these profiles were 'liking' 3,000, 4,000, even 5,000 pages," he said.
Facebook, which makes money from charging companies to show adverts designed to attract 'likes', said that it had "not seen evidence of a significant problem".
A spokesman for the social network stated: "We don't see evidence of a 'wave of likes' coming from fake users or 'obsessive clickers'."
But earlier in the year, the company admitted that between 5 and 6% of its 901 million member profiles worldwide could be fake, potentially up to 54m profiles.
The BBC decided to run a test, involving the creation of a Facebook page for VirtualBagel - a made-up company with no product to sell.
According to the corporation, the amount of 'likes' attracted from Egypt and the Philippines was "out of proportion" when compared with clicks from other countries such as the UK and US. Among the profiles that 'liked' VirtualBagel was someone from Cairo called Ahmed Ronaldo, who apparently worked for Real Madrid.
Graham Cluley, a security expert at Sophos, said that fake profiles are becoming a major problem on Facebook.
"Spammers and malware authors can mass-produce false Facebook profiles to help them spread dangerous links and spam, and trick people into befriending them," he told the BBC.
"I'm sure Facebook is trying to shut these down but it can be difficult to distinguish fake accounts from real ones."
Cluley also said that it was in Facebook's interests to downplay any problems with the 'likes' system.
"They're making money every time a business's advert leads to a phoney Facebook fan," he said.
A social media marketing expert at a leading agency told the BBC that Facebook advertising has "brought us very little return on sales".
The executive, who declined to be named, said that it was possible to increase engagement with customers on Facebook without actually paying the newly-listed company for advertising.
"The fans you get from advertising may not be genuine, and if they are genuine are they people who will engage with your brand?" he asked.
"The answer, more and more, appears to be no."
Last month, it was reported that Facebook has been testing a 'want' button that would apparently act similarly to 'like', but give a firmer indication that the person actually hopes to get the product or service.