Ewan's singing was an acquired taste - he had the same problems every singer had, especially in the early days - he once told me his early recordings made him cringe so much he couldn't bear to listen to them
He had problems with natural vibrato which he worked at and encouraged others to do the same - he devised exercises to tackle such problems
One time in London Singers Workshop, we agreed to listen critically to recordings of singers we know wouldn't mind our doing so
Pat brought in a recording of Ewan at his 4-square worst (a syllable per note) for discussion
That was, in my opinion, a perennial fault which varied throughout his life but never quite went away

Having said that, the litmus test for any singer is what you remember after each song - if it's the singing, then it has fallen short - if it's the song then the singer has succeeded
I now have all but one/two (?) of Ewan's albums - there isn't one I can't listen to over and over again ('Two-Way Trip marginal) - the 'Blood and Roses' set remain top of the list
I don't know how I will feel about the 78s as I haven't managed to get them yet
This is because I want to listen to the songs and not the singer
That's how I judge any singer
Jim