The pasuk says, “And if the Kohen examines the tzoraas and sees that it has spread, he need not (further) examine the yellow hair, the person is tameh (impure)” (Vayikra 13:36).
The Baal HaTurim points out that there are only two times in the entire Torah where we find this expression “lo yevaker” (he need not examine). The first time is in our parsha. The second time is in Parshas Bechukosai, regarding the laws of temurah (switched sacrifices) “lo yevaker (he shall not distinguish) between good and bad” (Vayikra 27:33).
The Baal HaTurim explains that there is a connection between these two pesukim: Since the person was guilty of distinguishing between good and bad (by speaking lashon horah), therefore the Kohen has no need to examine his tzoraas symptoms further and can declare him tameh (impure) immediately. The Baal HaTurim concludes “...for there are seven reasons that cause negaim (ritual skin-blemishes) to come”.
This is a classic comment of the Baal HaTurim because it is a riddle. Anyone is welcome to speculate over the meaning of this Baal HaTurim during his or her Shabbos seudah. My feeling is that the meaning of the Baal HaTurim is the following:
What is the aveira of lashon horah all about? When we distill lashon horah to its basic form, what does it consist of? Basically, lashon horah is about criticizing. It is the uncanny ability to look at a person or situation and find what is wrong — to latch on to the shortcomings and the downside. There is good and bad in all of us. We are not all good and we are not all bad. It is possible to look at a person and say “He’s stingy, he’s this, he’s that, etc.” But that same person also has positive traits. The chronic lashon horah speaker never sees these positive traits. He chooses to look at the bad and to criticize. He chooses to examine every person under a microscope, and always come to the conclusion that there are faults and shortcomings.
This is the meaning of the Baal HaTurim. When a person transgresses “You shall not examine between good and bad” (he always examines, always looks for fault and always criticizes), he will be punished midah k’neged mida (measure for measure). He will come to the Kohen and the Torah will instruct the Kohen “Do not examine any further.” Rule that he is tameh on the spot. Let him receive some of his own medicine. Teach the importance of “You shall not scrutinize (further)...” to he who always scrutinizes.
