I've found that they don't generally omit stuff, but the headlines and overall evaluations they give are suspect on more contentious items, almost to the point

I've found that they don't generally omit stuff, but the headlines and overall evaluations they give are suspect on more contentious items, almost to the point of a motte and bailey. So someone looking at the summaries will be mislead, but there's a more defensible opinion in the article proper. Now, they do pull tricks like choosing which version of a claim to debunk and sometimes seemingly hunting for more obscure weak man versions of a claim than the more popular ones. Or they will "fact check" something that is clearly an opinion, like someone's read of someone else's motives. The way I see it, though, they're hardly unique in this. Anyone skimming headlines is going to be badly mislead from nearly any source whatsoever.