There are some people who write things that might be "objectively" true but engender a "קרירות", a sense of apathy, indifference and detachedness, from Torah, Avodas Hashem or Emunas Chochomim. Or it will negatively impact his moral standards.
To give but one example: It is true that Chachmei Yisrael are not infallible - even Chazal. But harping on it creates a lack of awe and reverence that we must feel. That is one example of many. Sometimes, every word a person writes might be "true" but the article as a whole is Kfirah. So we have to be careful from such writing and from such people. [I could give examples of such people but - maybe against my better judgment - will refrain from doing so].
There are other people who write things that one can disagree with even vehemently but the sense is that the words were written with a passion for Torah and with profound Yiras Shomayim. So not every word is true but the spirit is.
Truth that is falsehood and falsehood that is truth.
