Are companies "bleaching" their online reputations clean?
Legislation that protects websites from lawsuits is cleansing negative comments from online forums, BBC Radio 4's You and Yours has been told.
Companies that threaten Section 5 defamation notices say they are a legitimate defence against false statements.
But one forum claims they lack the resources to challenge them, and criticisms are being "bleached".
Section 5 of the 2013 Defamation Act says that a person or company whose reputation has been damaged has to first attempt to sue the person who made the comments, not the website operator.
This takes some of the pressure off hosting websites.
But with the significant rise in online reputation management in recent years, a forum has claimed the orders are having unintended consequences.
The Legal Beagles forum offers free legal advice to consumers.
The administrators contacted You and Yours claiming they, and members of the forum, have been served with a continuous stream of Section 5 complaints about posts on their site.
They say the majority of complaints have come from the HR and employment law firm Peninsula Business Services after a number of discussions were posted about them.
Kate Briscoe, Legal Beagles' co-founder, claims it is having to remove defendable content about Peninsula due to limited resources, and posters are deleting their own comments because they are fearful of legal consequences.
"It's having a bleaching effect, because there is a very high take-down rate from our members," she said.
"They are put in the eye of the storm in front of this company, and threatened with legal action."
She added: "It means new businesses considering using Peninsula, aren't seeing a fair range of comments about them."
Peninsula Business Services claim that many statements being made on Legal Beagles' forum are false.
"We understand that all businesses are at risk of receiving fake, negative and defamatory reviews from rival companies, and we support the right of any company to challenge them," a spokeswoman told the BBC.
"On rare occasions, and only as a last resort, we have had to investigate what we believe to be false statements."
"Wherever we have encountered genuine clients, we have always resolved matters to all parties' satisfaction."
The effect is not equally felt across all forums though, as it appears size does matter when it comes to online communities.
Another site that has been served with Section 5 notices is leading parenting forum, Mumsnet.
In contrast to Legal Beagles, it takes a more positive view of the legislation.
Rowan Davies, head of policy and campaigns at Mumsnet, says people that post on its forum are more willing to stand up to legal threats.
By Joshua Rozenberg, BBC Radio 4, Law in Action
Can a company "bleach" its reputation by getting adverse comments taken off a website?
That depends on whether the website owner is prepared to call the company's bluff.
The website may be able to argue that the comments were not defamatory or that publishing them was in the public interest.
There's a risk that the website owner will then be sued by the company. But some websites may be willing to take that risk.
As for action against the person who posted the comment: Most people are not worth suing.
They would not have the money to pay damages and costs.
But no-one expected McDonalds to bring a libel claim against a couple of unemployed activists back in the mid-1990s.
So you can never be sure.
"Mumsnet users tend to pass on wisdom to each other, and are increasingly confident about standing by their comments when they know they're true," she said.
While Section 5 notices put the liability on the person who posted the comment, they do not completely protect websites from being sued.
If the person who posted the comment cannot be identified by the complainant, and the comment stays up, then the website can still be sued.
But as Kate Briscoe from Legal Beagles explains, even though they believe comments could be defended in court, the risk is too high to leave them up.
"To defend a defamation case, you're talking about tens, or hundreds of thousands of pounds," she said.
"It is a huge risk for a small organisation like ourselves, to risk the entire existence of the forum."
A simple Google search reveals several pages of companies dedicated to managing the online profiles of businesses.
They promise to tackle negative content, produce a positive profile, and make sure potential customers see businesses at their best.
Simon Wadsworth is a managing partner of one of the UK's leading online reputation management companies, Igniyte.
He says there has been a big rise in the last few years, of businesses trying to have negative content removed.
"Section 5s play a big part in what we do," he said.
"I've also heard the term bleaching, and I don't like it - it suggests you're sanitising something."
He added: "If a company genuinely has bad reviews, and you can't challenge them, then that bad reputation is deserved, isn't it?"
You and Yours is on BBC Radio 4 weekdays 12:15-13:00 GMT. Listen online or download the programme podcast.