I don't know anything about Bowles as a person at all, don't even know what he looked like. I did think The Sheltering Sky was a good book.
The list is definitely something I've gone back to a lot. I'm not sure why he gives some of the dates wrong--American Psycho was 1991, not 1988--and Hogg is just an extended rampage scatological grossout porno. It's not a bad book really (I'd definitely rather reread it than Dhalgren) but surely "the most shocking novel of the 20th century" would have to be something more political or such--that list's own ranking of The Public Burning at #4 is telling. That'd be a better choice. Hogg is basically an entire book of one of the sex sequences from American Psycho and with more poo.