In The Name of Allah, The Most Merciful, The Bestower of Mercy.
Al-Allaamah Saaleh Al-Fawzaan [may Allah preserve him] said:
The principle here is about warning against mistakes and deviance after identifying them as such. If the affair necessitates making known the name of an individual among the obstinate opponents so that beguilement does not occur through them, particularly those individuals with deviated views or deviation in behaviour and methodology, and they are well known among the people and a good opinion is held about them, there is no harm in mentioning them by their names and their methodology warned against. The scholars do research on the science of Jarh Wat-Tadeel and then mention the narrators and the criticism levelled against them. This is not done for the sake of personal (criticism), but rather to advise the Ummah in case they come across affairs from these individuals that are harmful to the Religion or lies against the Messenger [peace and blessings of Allah be upon him]. Therefore, this principle is first and foremost about warning against mistakes. But the person who made such a mistake should not be named if doing so would either do more harm or if there is no benefit in doing so.
If the matter requires that his name be made known in order to warn the people about his methodology, this is an act of sincere devotion to Allah in worship, an act of sincere devotion to Allah’s Book, an act of sincere devotion to Allah’s Messenger (by following his Sunnah), and an act of sincere advice to Muslim leaders and their common folk, especially if he (the one warned against) is active among the people and they have a positive view of him and buy his books and audio tapes. Therefore, there has to be clarification and warning because silence will be harmful to the people. His affair has to be unveiled, however, it must be done as an act of sincere devotion to Allah in worship, an act of sincere devotion to Allah’s Book, an act of sincere devotion to Allah’s Messenger (by following his Sunnah), and an act of sincere advice to Muslim leaders and their common folk, and not for the purpose of defamation or to satisfy one’s desires.
[An Excerpt from “Al-Ajwibah Al Mufeedah”. Question number 66. Page 162. slightly paraphrased]