there is only one case where I can believe that everybody bought their albums and listened to their music but, if you asked, nobody admitted to buy and listen to them... it's an italian band, active during the 70's and 80's, named SQUALLOR.
(but there is a precise reason for it!)
Try to explain it a bit, as possible...
The 4 resident members of that band were 4 of the most important italian songwriters/producers/talent-scouts who did regularly wrote/produced most of the greatest italian pop hits for a few decades... they were behind countless italian successful singers!
It would be way too long to make a list of what they produced during the 60s/70s/80s/90s but I can mention just a couple songs which are also well known abroad because they were covered by Laura Branigan in the 80s to finally break into the international market: "Gloria" and "Self Control" , also "Ti Amo" (no need to say that, if I just have to listen to these songs, I would prefer, by far, the original italian versions of such songs by Umberto Tozzi and by Raf).
So, these 4 important italian songwriters/producers during the day they worked in a very serious way with the other singers and, after dinner (and usually very drunk!) they used to return to the studio to record some totally ABSURD stuff!
I mean, they used to make some music as a base and adding on it some (often improvised) spoken words, full of terrific humour, full of swear words, totally politically uncorrect, like kidding the religion, the politicians, the sex, the gays and just anything you may think about!
Or, they used to also make some parody songs (i.e. something in the style of the typical melodic/new-melodic pop songs from Naples) which were even more full of heavy swear words than their "spoken words" songs.
Nowadays, such kind of stuff would get totally censored and would stay unreleased, btw, also back in the 70's and 80's they had quite some problems with censorship but they simply didn't care! They were so powerful into italian music industry that, even if no radios ever broadcasted their "songs", their albums were widespread in the shops anyway... and LOTS of people (myself included, during my teen years) used to listen to them while laughing with tears but we used to listen to those albums in secret or together with just a couple selected friends!
Everybody knew them but nobody would admit they knew them! (myself included)
They were, most likely, the first ones who made such kind of "music" and, for sure, they were the very best of their kind... EVER!
At now, such 4 incredible guys are all dead and we miss them a lot... nodoby else made me laugh like they did!
So, if you asked here in Italy, nobody bought their albums but they were regularly in the TOP 10 chart! Then, nobody admitted they bought their albums... as for myself, I would have felt embarrassed in going to the shop asking for any of those albums then I used to have them on home recorded cassettes, which I used to keep well hidden.
Also, their cover artworks were terrific! Usually joking around double meanings on the album title but with the cover artwork which made it just clear on the bad meaning!
If you wish to check some of their cover artworks, just give a look at their discography:
https://www.discogs.com/it/artist/368478-Squallor
Unfortunately, if you don't understand italian language AND the dialect from Naples, you just cannot enjoy them at all... and, of course, any attempt in translating them would miserably fail, because it's impossible to properly render their corrosive sarcasm and all those swear words into another language. (i believe italian language is the one with the most wide selection of heavy swear words worldwide)
Then, the SQUALLOR sold millions of albums but "nobody bought them"!
EDIT: just a couple cover and album titles explained...
album title: "Palle" (Balls):
album title: "Pompa" (Pump) but it's also a slang meaning a bl*w job:
album title: "Cappelle" (no need to explain, after watching the cover artwork!):
Album title: "Scoraggiando" ("discouraging" but also resembling "scorreggiando" which means farting):
and so on....