R' Pinchos of Koretz Zatzal says that even if the entire world: מִּ תְּ חִּ לַ ת בְּרִּ יאַת הָּעוֹלָּם וְּ עַ ד סוֹפוֹ (from the beginning of creation, till the end) would be total Reshaim, Chas V'shalom, it wouldn’t bother Hashem, since He is total goodness. But when a Tzaddik sees a Zil'zul in Kavod Shamayim and he has pain, this causes all the Tzaros, Rachmana Litzlan. When Noach came, it caused the Mabul, etc.!
R' Tzadok HaCohen Zatzal says the same idea, that despite all the Tefilos that Tzaddikim have to save the world, their own negative opinions and complaints about the Dor cause the Tzara in the first place. Always see good and say good about your Dor (of course, if there is a To’eles, that is a totally different story). It is extremely difficult for a Tzaddik not to be upset with the evil of the world, and the only Tzaddik who is: נִּ יצָּ ל spared from this completely is Moshiach!
The Sefer Aderes Eliyahu (written by the Ben Ish Chai) says that saying a Zechus about Klal...
