It oughtn't be. You might not like their opinion pages -- yes, they're typically left-wing -- but The Guardian's reporting is absolutely top notch; amongst the best in the world.
No. They constantly blur editorial features and news. The most shared posts are ludicrous hysterical nutters that they give a platform to because it generates clicks.
How do you differentiate between opinionated/politically biased pieces and general reporting ? What's the criteria for evaluating good (ie trustworthy) reporting ? Curious to know.
They usually say that the piece is an opinion piece.
Opinion pages are clearly set apart from news reporting. In The Guardian, opinion pieces appear in the "Comment is Free" section.