Advisers paying to use VouchedFor could be forking out £99 on average per enquiry, a report has found.
Meanwhile advisers using Unbiased will be paying £48 on average for each enquiry.
But the report, compiled by Sense network’s Phil Bray, said this may be because some advisers are not committing time to making the directories work for them.
Mr Bray’s research showed conversion rates for both directories are similar, but similarly poor, with around 40 per cent of advisers reporting that only one in 10 enquiries become clients.
But this masks a more complex picture, with 25 per cent of advisers using either Unbiased or VouchedFor converting more than 50 per cent of their enquiries.
Mr Bray said: “It’s clear that used correctly both Unbiased and VouchedFor can work well for the majority of advisers. The question therefore has to be how can best practice be shared amongst advisers?
“All three stakeholders, Unbiased, VouchedFor and advisers have a part to play. The directories need to listen to their customers, take on board constructive criticism and help spread best practice through training and support.
“Advisers, on the other hand, need to commit time to implementing best practice and ensure the directories form a core part of their marketing strategy.”
Unbiased proved the most popular directory, with 26,000 advisers, while VouchedFor has 4,800.
One in five advisers uses both directories but usage of no directory is widespread, with four out of 10 using neither.
Most advisers don’t appear to like their directory, with 54 per cent of Unbiased users and 58 per cent of VouchedFor users admitting to feeling less positive about them over the past six months.
Mr Bray said that to get returns on investing in a listing, advisers would need to demonstrate commitment to them, pay for a listing and invest time in making sure their entry looked up to scratch.
In a statement VouchedFor said: “Clearly, many advisers get great value from both directories, while others leave frustrated.
“As a marketplace we can only control so much, and VouchedFor is designed to reward those who put the most into helping clients.
“We work hard to share best practice among advisers. We have a team of ‘member coaches’ who are always on hand to help, and a comprehensive Help section on the website.”
It added that users are encouraged to start on the free plan to build up their reviews from existing clients before paying for a listing.
Meanwhile an Unbiased statement said: “Balancing the interests of consumers and advisers is always a challenge, and it demands an evolutionary process.
“So we’re continually monitoring the effectiveness of Unbiased and seeing how we can improve it for all users – even week-by-week and day-by-day.
“We’re lucky to have an exceptional team who understand the issues from both an adviser and a consumer perspective, enabling us to deliver premium value enquiries at the lowest market cost.