About the only thing I ever watch on PBS is This Old House, Ask This Old House, New Yankee Workshop, Hometime, and Motorweek. Other than that, it's not worth watching. Even programs like Nova and Scientific American Frontiers With Alan Alda have a Liberal slant to them.
I'll agree with you on the science shows having a liberal slant. But, according to some of these posters, New Yankee Workshop is a liberal show too. Can't say I agree. Norm Abram (the host) may be a dork, but that doesn't mean he's a liberal dork. LOL And, well, chances are good that he is liberal, but I've never seen any of his political philosophies bleed over into the show. As Freud would say, Sometimes a miter joint is just a miter joint. : )