U2 is fascinating to me because its fanbase is seemingly just Gen X. Baby Boomers don’t listen to that shit, I’ve never met a millennial who liked it. Just a narrow group of teenagers/young adults who grew up in the 80s. I think most bands that go for decades have a much wider fanbase.
Aerosmith was cooler & more relevant in the 90s to me than U2. I see U2 I think of Beavis screaming Boner.
U2 are one of those bands that nobody will admit to liking, but that somehow sell gigantic numbers of records. Though I'll agree on the GenX thing, I'm from the next generation after that (early millenial) and even by my time U2 were a desperately uncool band for losers. Not quite dad-rock, because our dads hated them too, but I guess older-brother-rock or lame-ass-cousin rock. Other bands like U2 include ABBA, Coldplay and Train - I've never met
anyone who has admitted to liking those bands, but someone is buying their albums and going to see their concerts. I've even met unironic Imagine Dragons and Nickelback fans, but nobody, ever, will admit to liking U2.
There are of course bands that are the opposite, and tend to be red flags: bands that people say they listen to but that very few people actually do: Death Grips, Die Antwoord, most Black Metal. Music that exists to be seen to be listening to, rather than just to be listened to. Not saying that any of that music is bad, necessarily, but you have to be suspicious of someone who has curated their music taste to impress people, they're usually deeply insecure and shallow.
Back in the late 2000s/early 2010s you had "Landfill Indie". This one is a bit personal to me because of my visceral hatred of the Strokes. The Strokes make bad music, sure, but it was what their breakthrough in 2001-ish did to the indie music scene. Before "Is This It", indie music was creative, weird and passionate - stuff like Radiohead, early Muse, Starsailor, Weezer, but when the Strokes turned up with their rich parents and industry connections all that was crushed and swept aside in a tidal wave of leather jackets, power chords and floofy hair. Suddenly Indie music was about who wore the most fashionable clothes. All the bands looked and sounded exactly the same because they were trying to be the Strokes. They were called "The [something]s", they hacked away at the Gibson ES-335s their parents bought them, and they all posed and preened and tried to get on the cover of GQ. The music was an afterthought. And the people who liked that absolute garbage, particularly the British scene which produced utter talentless dross like The Enemy and The View, were, in the truest sense of the word, posers. They didn't care about the music any more than the bands, they just went to the gigs to look cool. This was the genesis of the hipster phenomenon of the 2010s that raped the art, fashion and music worlds with a dick made of daddy's money and fashionably torn jeans. And some of those people are still around, and those people are walking red flags. If you still like the Strokes or Razorlight now, you are the very definition of "peaked in high school" and should be given a very wide berth by everyone.