You just said you don't trust the evil right-wing blogs.
It's got very little to do with blogs being evil or right-wing, and far more to do with spouting unsourced assertions. And yes, evil left-wing blogs do this too.
But when Bernie does it his numbers "have merit" and are "mostly true." When Trump does it he's "misleading" and "mostly false." Fuck you politifact.
The difference is that Sanders qualified his statements to refer to a more specific demographic:
"If you look at Latino kids between 17 and 20 who graduated high school, 36 percent of them are unemployed or underemployed. African-American kids are unemployed or underemployed to the tune of 51 percent."
(emphasis mine). Trump didn't; his claim was far more sweeping:
"If you look at what’s going on in this country, African-American youth is an example: 59 percent unemployment rate; 59 percent," Trump said.
Politifact asked both candidates to clarify; Sanders pointed them at research supporting his more-specific claim, while Trump did not respond. They speculate that Trump perhaps meant everyone who wasn't working, including students and others who weren't even looking for work, which is not the official definition of "unemployment rate". There's a reason the BLS lists Employed and Unemployed rates separately; they measure different things.
Surely you can see the difference between those two claims? Trump's broader claim, using the normally-accepted definition of "unemployment", does not come close to the current figures. Sanders' more-specific claim was supported by research. If Trump wants his assertions to be accepted, he either needs to be more specific, or to back them up with sources.
More importantly, Politifact a) examined the actual words said, with some context, b) provided sources for their figures, and c) fully explained their reasoning. That's all we can ask a fact-checking site to do, as it allows us to see why they made their judgement. You're free to assume a different interpretation of the words if you like, and also to link to other fact-checking sites that hopefully provide equally lucid reasoning. But claiming that "they said the same thing and Politifact supported one and not the other" is clearly not the case.
Also, I did not claim that the left doesn't tear down sources (they certainly do), I said "they rarely work this hard to tear down every reputable source". Perhaps we have different definitions of "reputable"? My idea of a reputable source is one that provides well-researched sources (peer-reviewed where possible) for their claims, and makes it clear when they are indulging in speculation. There are plenty of blogs on both sides that fail at this, but fact-checking sites generally try harder. I'm sure Breitbart comes out with well-researched pieces too, but there's a lot of articles full of unsourced assertions mixed in with them, which does not do their reputation much good. One can hope that their higher-quality points are picked up and repeated by more reputable sites, where they may get a broader audience.
My point was less about political mud-slinging, since that's a god-awful mess on both sides that I have little interest in (not being American), but more about the common theme of science denial that a fairly large proportion of conservatives seem fond of (in my country too). That this is being extended to fact-checking sites worries me, particularly the assumption that any fact-checking site would automatically be assumed by the right to be biased towards the left. Is objective truth really considered so hard to pin down, now? Are there no well-sourced fact-checking sites that the political right feels comfortable with?