As you have come across this post, I am going to assume that you've also read the plethora of articles some Muslims/groups have written to defaming, "expose" and reject others and their opinions. I don't think it necessary to give any examples. However, in this regard there is an important incident that took place leading up to the conquest of Mekkah - and inshaAllah it will give us time to reflect upon the manners and methods that we use when dealing with others who have made mistakes.
One of the Companions (may Allah be pleased with him) due to his own reasons and reasoning decided to inform some of the people in Mekkah of the pending conquest. The Prophet (peace and blessings be upon him) was informed of the situation through revelation and as a result the messenger was stopped and the message prevented from being sent. This particular companion was then questioned so as to why he had done what he did. He did not deny his mistake and provided his reasons and reasoning; albeit this was a mistake that the Prophet (peace be upon him) clearly and strongly stood against. As a result, Allah revealed the verse that states:
"O you who have believed, do not take My enemies and your enemies as allies, extending to them affection while they have disbelieved in what came to you of the truth, having driven out the Prophet and yourselves [only] because you believe in Allah , your Lord. If you have come out for jihad in My cause and seeking means to My approval, [take them not as friends]. You confide to them affection, but I am most knowing of what you have concealed and what you have declared. And whoever does it among you has certainly strayed from the soundness of the way." (60:1)Clearly this companion (may Allah be pleased with him) made a mistake. And, herein lies the connection to where we started: dealing with those who make mistakes. Although this was a mistake and could have resulted in harm for the pending conquest, the Prophet (peace and blessings be upon him) dealt with this companion in a noble, kind and merciful manner because the Prophet (peace be upon him) knew that this companion had done great deeds in his life. This method reinforced the fact that the bond of Islam is the strongest bond, even if one makes a mistake. Another point for reflection within this incident is that the Prophet (peace and blessings be upon him) did not only look at the specific details related to that mistake, he looked at the overall person and overall efforts of this companion - and one of his great deeds was his participation in the Battle of Badr.
Herein lies the benefit for us today: those who have given decades in the pursuit of knowledge for the sake of Allah are to be honored and praised. They are not free from making mistakes or free from the possibility of giving incorrect rulings. With that in mind, let us look at the greater context of scholarship and scholars before defaming, exposing and rejecting someone due to a mistake, error or otherwise. Just as the Prophet (peace be upon him) did, we must judge people justly - not looking at one ruling and casting vast generalizations and making overarching conclusions. When a person has spent an entire life learning the diin and spreading the message of Islam, it is not fair to cast judgement based upon one mistake.
It is common for us to see scholars today vilified and "exposed" not in making mistakes but after having strove to find the truth in a ruling - even if the result may have been incorrect. As we know from the Prophetic narration, a person who strives sincerely to give a ruling based upon what is known, there is reward in that - whereas today people have taken to slandering such a person. May Allah protect us from that.
Furthermore, we see from this and other examples that is was not the methodology of the Prophet (peace and blessings be upon him) to highlight the mistakes of others. Such differences or corrections must be done in a scholarly way and done with the manners of Muslims - not in personal attacks and neglecting to mention such a persons good deeds. Regarding that companion (may Allah be pleased with him) Allah's Messenger said:
"Speak nothing to him save good [words]" (Sahih al-Bukhari)