I used to listen to NHPR a lot when I had a long commute one summer and would occasionally tune in. My biggest complaint isn't that NPR is too liberal, only that it is very surface-thought in its discussion of topics. Too often a story will raise what seem to be obvious and interesting (but maybe difficult) questions and the journalist or interviewer will just move on.
I dimly have one example in mind, a government agency (port authority?) in Oregon had millions in carbon credits (tax offsets) that it couldn't use, so it sold them to some other Oregon company for cheap to some corporation. Imagine its $5m tax credits that it sold for $1m. The company could then offset $5m of taxes. This was billed as a good deal for the port authority.
Of course as described it's really the state of Oregon losing $4m by selling the credit on the cheap, which seems totally insane. This was never discussed. I gave up after that story.