I guess theres a difference between a guilty pleasure and an alternative like, a bit off piste...
Guilty pleasure..
Marc Bolan. HATED his / their stuff as a teen, too 'teeny bopper'...but as I aged, found more of their music and actually REALLY like it.
Off piste ?
Ethnic music, often with fusion of modern style.
Father Seraphim, wonderful religious chant / music even through im not religious.
Katya Chili, often a Ukrainian style traditional based music with her very individual style.
Malcolm McLaren, particually his rap fused with opera.
Gennady Tkaichenko, a strange but spellbinding style of extraordinarily powerful voice.
Some odd stuff in there i think