Bill Whittle had an essay on this once

What to do when the Left uses the truth to lie.

So how does one deal with that debate, where links to CNN are lobbed out like candy on Halloween? The short answer may be to do as they do when they dismiss Fox News. Your source is extremely Leftist, go away. This, however, contains a weakness. The spin, the rot, has infected academia as well. So many of the academic sources for information are similarly contaminated, though again they may be perfectly true in the sense I’ve described above. The real answer, though anything but short and simple, may be to go find the information out for ourselves; to document it and record it ourselves. 

In other words, we may have to give up the expedient of looking into the palantir, and just find the answers on our own, the hard way.

I recall Bill Whittle using the Fat Fuck from Flint as an analogy.  Take a bucket of sand from Malibu.  Remove all the black grains of sand, set them aside, and then repeat.  Get enough black grains of sand to fill a bucket, and then around with your black sand and declare that this is the sand of Malibu Beach.

Is it the truth?  Yes.  But is it also a lie?  Yes.  Because the sand of Malibu is almost white in color.  You have to work a long time to pull out just the black grains of sand.  But that's what the Left does.  They spend hours and hours pulling out just the black grains of sand, and should you hold up a bucket of sand from Malibu and say "But, this is what Malibu beaches actually look like" they attack you for daring to call them liars.

Some of the left is stupid.  And the rest of the Left is evil.