Just had an idea for this thread after encountering a weird situation. There's a song called "Majima no MajiROCK" written for the Yakuza games and it's meant to be sung by one of the protagonists as in-game karaoke, but the lyricist for the song sings the "default" version you hear on radios etc. and he's actually a really good singer. Like, "better than the intended singer" good, especially in the chorus. The thumbnail for this is cursed but I can assure you the singing is not.
Anyone else ever encountered people who are patently not singers but sing really well?
It doesn't have to be as weird as that, just someone who doesn't seem to have any singing material or history at all (ie. not even qualifying for "part time singers") but has a surprisingly good voice.