Personally, I don’t like the dismissals of papers because of editorial slants, regardless of the information entailed. This includes The Guardian and the Daily Mail, and especially when it’s not an opinion piece. It’s unthinking and not very critical of thinking. It wasn’t the Guardian that triggered this issue about Gove, for one. The nature of it is therefor not affected by the Guardian’s slant.
However, the latter is less reputable. I’d say the Telegraph is a better analogy for the Guardian.