You're probably too hip to explain that, but I will offer the opportunity anyway.
It's pretty self-explanatory I thought, coming as it did in response to a comparison with James Brown, Miles Davis, Captain Beefheart and other musicians who were reportedly not nice people in their private lives. Do their personalities make it impossible for me to enjoy their music? No, because their music is for the most part uncontaminated by the specifics of their unlovely traits. Apart from the instrumentals, which I have said I can often enjoy, Zappa seemed pretty determined that you never get very far into one of his records without being reminded of what a sneering, contemptuous, audience-hating, sexist, homophobic, scat-obsessed creep he was. I love Chuck Berry's music, but if he rarely got through an album side without bringing his sexual inclinations into it, I'd start having a problem. So no, artists don't have to fill out a personality-assessment form for my sake. Make creepy records, though, and I reserve the right to be creeped out by them.
If you read Ben Watson's book
The Negative Dialectics of Poodle Play, you'll find that the theory behind Zappa's vaunted "Conceptual Continuity" was the creation of a gigantic, genre-spanning, lowbrow-meets-highbrow body of art with not merely an absent, but a
malignant, moral center - it was sort of kind of well maybe the point of Zappa's whole career. Watson describes Zappa as providing what he calls "a travesty of power," and throwing up intentionally unresolvable contradictions (social liberal/fiscal conservative; anti-consumerist/petit-bourgeois; the aforementioned lowbrow/highbrow, etc.) as the primary means of creating a massive art project that cannot be comfortably absorbed into any canon. I think there may be something to that - Zappa doesn't really fit into the classic rock canon, nor does he fit into the punk canon, nor the jazz canon, nor the avant-garde canon, nor the classical canon, without some major reservations about the questionable morality undergirding both his work and his person. I think he wanted to make something big and undigestible, something that stood outside of every extant tradition.
Watson's contention about Zappa's motives is that the lyrical content of much of his work - the sexist, scatological, homophobic stuff - was not meant to represent the actual feelings of its creator; he was primarily a satirist and a social documentarian, not an artist expressing his feelings. I dunno about that. I've read enough about the guy to get the impression that he was a homophobic, sexist jerk in real life too. He had little use for friends, defining a friend as "someone who thinks they can borrow money from you." Most of his inner circle described him as getting progressively even more cynical and bitter and isolated from the real world as he got older. However, I think his misanthropic persona was somewhat created from whole cloth, at least in part, as he knew his "weirdness" as a person helped sell records (to an ever-dwindling cult, sure, but they sold enough to keep his family comfortable).
Honestly, I think Zappa was psychologically scarred by the incident in his youth when he was arrested for making a "pornographic" audio tape, and he used his ENTIRE career as a vehicle for getting back at the cop who busted him.
Like I said, he sure made it difficult to be a fan.....(maybe that was the point....I give up.)