This thread has really got me thinking and analysing.
I didn't know that "Sunshine on my Shoulders" track Jenna, and checked it out. My cheese alarm didn't go off too badly in fact, possibly because I've never heard the song before. It made me realise that over-familiarity is maybe another cause of cheese. A bit like the first time a DJ played "YMCA" at a wedding and everyone did the dance, it wouldn't have been cheesy, but now it would be, because its been done soooo many times. Maybe sometimes it is not the song itself but the overexposure it gets.
Which brings me back to James Blunt! Disclaimers first: As YD rightly says, it was a million-seller and Mr Blunt for sure does not need any lessons in song writing from someone like me who has never made a single penny from his music. I also don't have a problem with JB himself - I quite liked his follow up song "1973". And one person's cheese is probably another person's classic genius. BUT... that "You're Beautiful" song still brings me out in hives. I analysed my reaction last night and partly it is overexposure (there was a time when you couldn't escape the damn thing on the radio...) but it is also definitely the song itself. Take the first verse and chorus:
My life is brilliant, my love is pure
I saw an angel of that I'm sure
She smiled at me on the subway
She was with another man
But I won't lose no sleep on that 'cause I've got a plan
You're beautiful, You're beautiful, You're beautiful, it's true
I saw your face in a crowded place and I don't know what to do
'Cause I'll never be with you
My issues with it are 1) the predictable rhymes (man/plan, true/do etc), 2) the laziness of the contradictory lyrics if you think about them for a millisecond, e.g. "I've got a plan" then 2 lines later "I don't know what to do..." - well it's not much of a plan then is it James?!, 3) the lack of interesting story in the entire song (a guy sees a pretty girl in a train and then... nothing at all happens). 2 + 3 are probably not the cause of cheese in themselves, they are just lazy writing... but I think that amplifies the cheese, or at least fails to counteract it. I'd probably forgive predictable rhymes if there was something interesting going on in the story for example.
So maybe what we've got so far as cheese-causing culprits are:
A. Use of cliche (lyrics or music)
B. Predictability (especially of rhymes, also of music)
C. One-dimensional overly happy or sad emotions without nuance (which could come from the music itself, like your 'C Major" version you say)
D. Overexposure / overfamiliarity of the song
I'm getting the feeling you can get away with SOME of these in a song but not ALL of them (which is why I was OK with "Sunshine on Your Shoulders" - for me it had lots of 'C' and a bit of 'B', but not much 'A' and zero 'D' as I'd never heard it).
OK, I'm ranting. Sorry. I will now listen to "You're Beautiful" on repeat for an hour as penance.