One pet peeve that I'm experiencing more frequently recently is the claim by some that vinyl LPs are better than CDs. Now sure, "better" is a relative term, but many of these people claim that LPs are better in a technical sense than CDs, which is patently false. In every objective, measurable way CDs are better: SNR, channel separation, frequency response, etc.
I can completely understand some people liking the sound of LPs better, but that's due to the inherent limitations and distortions of the format that they've grown used to over time rather than any technical superiority. I can also understand liking LPs for other reasons like nostalgia, album art, liner notes, and the tactile feeling of putting a record on a turntable, but wish they'd stop making claims they can't back up with test results.