These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Covered Up: "El Condor Pasa (If I Could)", which is just Simon's lyrics sung over the Los Incas version of the famous Peruvian folk song "El Condor Pasa" by Daniel AlomÃa Robles. Similarly, "Scarborough Fair/Canticle" adds new lyrics sung in counterpoint to the original folk ballad.
Crowning Music of Awesome: "The Boxer", "Cecilia"... Heck, let's just include most of their catalog.
Everyone Is Jesus in Purgatory: Tons of interpretations of "The Boxer" say that its refrain of "Lie la lie" means something significant (e.g.: that the singer is actually lying about his whole tale). Paul Simon has gone on record as saying that he just couldn't think of any words to sing there.