If you listen carefully to everything that is sung on the S&G version, I think you will find it is not "sugar slop".

True Scarborough Fair itself appears to have been "prettied up" by leaving out several verses so that the sense of two former lovers having a go at each other has got lost, but as Diane Easby pointed out much further up the thread,

<<Paul Simon took Martin Carthy's arrangement and set it in counterpoint to the tune of his own composition "The Side Of A Hill". And very clever it was too.>>

In fact Paul Simon partly rewrote "The Side of a Hill" for SF, but the song was in essence, the same. Here are the original words of "Side of a Hill";

On the side of a hill, in a land called somewhere
A little boy sleeps alone in the earth.
While down in the valley a cruel war rages
And people forget what a child's life is worth

On the side of a hill, a little cloud weeps
And waters the grave with its silent tears
While a soldier cleans a polishes a gun
Which ended a life at the age of seven years

And the war rages on in a land called somewhere
And generals order their men to kill
And to fight for a cause they've long ago forgotten
While a little cloud weeps on the side of a hill.

The first verse is where the main changes are in SF.