Can I help make some recommendations? I personally like to choose the worst books by popular authors. So The TommyKnockers & From a Buick 8 by Stephen King. StarBlood, Demon Seed & 77 Shadow street by Dean Koontz
A Dark Matter by Peter Straub, I bought at CVS because I saw Straubs name on it, it ended up being absolutely atrociously horrible (i love Straub though, just a bad book)

Some of my least favorite books are mostly really popular books that I thought were really bad. I actually liked some of those books you listed above. But it's a matter of opinion which makes it hard to pick out the absolute worst books. I'm mad that a bunch of literary classics made it onto that list though.