Broadband customers do not often know the average connection speed they will actually receive after signing up to a deal.
Forrester Research Analyst Ian Fogg has told the Times that while prospective broadband subscribers may be able to compare 'up to' speeds, they are rarely aware of the actual speed their connection will provide.
Mr Fogg used the example of Virgin Media's 20Mb offering, which was found to only offer average speeds totalling half of those advertised.
He told the publication: "The problem with the current advertising of broadband is that consumers can distinguish between providers using cost and top speeds, but they cannot say which provider offers the best quality or is most likely to give them the speeds they want."
Experts recently told the Guardian that speeds on Virgin Media's 50Mb service are likely to slow once more users sign up to use the service.