When i play a game, im used to the theme music popping in at certain times that i'd get used to after a while.  
After a few hours you'd know which sounds would play when.. u know ? 
 
But with this game, the game sometimes played shit out of the blue, sometimes music i never heard before and for no apparent reason..  it makes you think "do i have to do certain things to be able to hear the whole soundtrack? what if ive beaten the game without hearing 20% of the whole thing ?" 
 
Lemme give you the latest example : Right now im on my 2nd playthrough and im in Mexico, almost done (thank god). so i missed the american landscape and crossed the border on my horse to go dick around Armadillo.. all of a sudden while around Rio Bravo, a really heartwarming piece of theme music played that went well with the sight of me racing the wind on my horse 
I was like "where the fuck did that come from?" 
 
 
what do u think? most confusing soundtrack ever ?

I just pictured John Marston saying "WHERE IS THAT MUSIC COMING FROM!?!? *frantically shoots revolver at the sky* "

Considering I own the soundtrack and therefore know all the songs in the game, no it's not confusing. There are three songs with lyrics that play at scripted moments and a whole slew of other songs that just seem to slip in naturally at different places.  
 
@luce said:

" I just pictured John Marston saying "WHERE IS THAT MUSIC COMING FROM!?!? *frantically shoots revolver at the sky* " "

  This video explains how the non-scripted music plays during the game... somewhat. It is also pretty interesting.