He accused Schoenberg, after his death, of the “most ostentatious and obsolete romanticism.” Webern was “too simple.” Berg suffered from “bad taste,” Ravel from “affectation.” Twelve-tone music in its extant form was overrun by “number-fanatics” who engaged in “frenetic arithmetic masturbation.” Boulez’s teacher, Olivier Messiaen, produced “brothel music.” John Cage, who was at one time an ally of Boulez, became a “performing monkey,” and Karlheinz Stockhausen, likewise, a “hippie.” The American minimalists displayed a “supermarket aesthetic,” the American serialists had a “cashier’s point of view.” Brahms was a “bore,” Tchaikovsky “abominable,” Verdi “stupid, stupid, stupid!” And so on.
"Well, Shostakovich plays with clichés most of the time, I find. It's like olive oil, when you have a second and even third pressing, and I think of Shostakovich as the second, or even third, pressing of Mahler."
Incidentally, between this and The Rest Is Noise, I'm pretty sure Pierre Boulez ran over Alex Ross's dog or something.
This wasn't a constant eccentricity but a one-time response to an outbreak of shingles, at least according to this source:
The viewer may be surprised to see Pierre Boulez conducting wearing sun glasses but the conductor, who was suffering from facial shingles which made him extremely sensitive to light, wanted to carry out the scheduled recording.