In general, don't attack Japan in front of SamuraiBlue, and I shouldn't have brought up Biwa. My point is not to relate an exact equivalency; most Chinese are impressed by social ethics in Japan, but to note that the concept of China as highly polluted is only true in parts. What about Kunming? Lhasa? Urumqi?
TBH, the real reason I think the Japanese dislike the Chinese is because the Chinese have their baby pictures. The oldest historical mention of Japan is in Chinese histories, and they're not very flattering. What is intrinsically notable about Japan is how far they've come; during the Tang dynasty the Japanese relief fleet for Baekje was thrashed by combined Silla-Tang forces. During the Imjin Waeran, the Ming forces were not decisively superior against the Japanese, and without the intervention of Yi Sun-Shin the Ming would have been unable to prevail in a renewed war. And during the early part of the 20th century, if the Japanese had chosen a gradual policy of imperialism, as the Manchus had done so, they might have been able to gobble up China.
That said, SamuraiBlue: Here's a strange example from Chinese history. During the High Qing period, the Chinese had a similar status in the Western world as Japan does now; Voltaire used the Manchu monarchy as an example of enlightened rule, as opposed to the despotisms of Europe, and Chinoiserie was in vogue. Yet Western observers, while praising much of China, found issue with the incessant Chinese habit of courteous lying, not unlike the Japanese obsession with harmony. I would trace part of China's civilizational decline to this lying; the inability to identify and rectify cultural and societal issues made China unable to adapt to its own decline and the challenge posed by the Western powers and Japan.
I hope you get what I'm implying, right? I know that Chinese can be extremely critical of their own society in their own groupings, but when attacked by an outsider, as we are doing to you now, they tend to become rigid and defend their society. From what I've seen, Japanese can be critical of, say, Abe (Ahonomics, for instance), but will keep up appearances in front of outsiders.