Chazal say (Me'am Lo'ez) that Moshe was somewhat upset with Yehoshua, and he said: “You should know what a Milchama (war) sounds like, since you fought Amalek; you should know better what these: קולוַּת noises are all about! I would suggest that a Tzadik who has an Ayin Tova and who looks to see only good, won’t Chap that something evil is going on, since he loves seeing only good.
Indeed, by the Chet of the Meraglim, where 10 Shevotim saw evil, Kalev and Yehoshua saw only good and they said: טובָּהַּהָּאָּרֶץַּמְאֹדַַּּ מְאֹדַַּּשלחַּידַּז the land of Eretz Yisroel is very, very good. Similarly, when Yirmiyahu HaNavi saw smoke coming from Yerushalayim, he thought that it was Ketores, since he assumed that the Yidden were doing Teshuva. Actually, it was the Churban Bais Hamikdash. There is a similar story about Moshe making such a mistake (Rashi). Dovid was especially full of Ayin Tova, and he saw good in Shaul during the worst Redifos (persecutions) that he had from him.
Good People Like to See Good and To Report Only Good
He praised Avner and Ish Boshes, although they were his adversities. When his son Avshalom was killed in battle, and he saw Achimatz running towards him - he said: “This is a good man who reports good news”. We see that good people like to see good and like to report only good. Chazal say that a person who is a: יָּאַּרִַּיגונֵַּּס ַּ advocate on behalf of Klal Yisroel, Hashem uplifts him. And here we see the leadership qualities of Yehoshua.
A Yid has to work on avoiding politics, and to avoid getting involved in looking down at other Yidden. We have to emulate Hashem, who is total goodness. Just as we try to grow in Yedi’as HaTorah, so it’s K'dai to make sure you’re a first class Am HaAretz in not knowing the “dirt” and shortcomings of your brothers; especially of different groups in Klal Yisroel. You’ll get plenty of Schar for your ignorance.