Have a feeling these are a bunch of pulled quotes over several years. The Bowie quote is probably from 73, at least a year after what CCR pretty much fell apart.
We need more rock stars talking shit about each other. These days, every indie album is a Pitchfork 8.9 masterpiece and every artist's twitter is enraged if they are given anything but praise. Competition is good
I just looked it up. Lou's comments on Zappa were in 1966, when he just had Freak Out under his belt. I'm assuming Lou saw his as a parody act of sorts with no real musical chops. I'm sure his opinion of him shifted considerably over the years.