Title is self explanatory - which artists or bands are considered really daggy, old fashioned, out of touch, etc etc...but you just can't help still listening to them frequently, despite all the derision of your mates or family.
May as well put the hand up and I know plenty on here will be sniggering knowingly at what is coming...
Little River Band. Love the harmonies, love the songwriting (When Frank Sinatra declared that "Reminiscing" was one of the only songs he wished he'd written, it said something!), and still keep them on frequent rotation.

...especially some of the stuff when the tensions within the band were at their highest (notably "Man On Your Mind", "Take It Easy On Me" - George Martin, legendary Beatles producer, produced the album "Time Exposure" and said at the time that the politics within the Beatles were an absolute picnic compared to those of Graham Goble, Glenn Shorrock, Beeb Birtles and the other members)
I'll stand in the corner now

...and see who's next!
Can you guess where I'm calling from, the Las Vegas Hilton...