Something that bugs me is when somebody sings a version of a song as arranged by a particular artiste or band in their own distinctive style. For example Steeleye Span's "John Barleycorn". Nothing wrong with the song, the arrangement or the band, but in this case it comes over as if the singer doesn't know the original song, or is incapable of doing their own arrangement, and is just parroting the record.

Not that I haven't learned stuff from records myself.