A Question of Talent or Taste?

So I'm looking at the NY Times Best Seller List this week and once again I am astounded by what book is on top. It's Mary, Mary by James Patterson and that just floors me.

I've only read one James Patterson book, Honeymoon which suckered me in with its designation as the 2005 International Thriller of the Year, whatever that means. I found it to be one of the worst written books I have ever read. A vapid, empty book, full of unbelievable characters spouting some of the tritest dialog I have read in years. I would read some of it out loud to my wife and we would both burst out laughing. From inept plotting to dull, lifeless characters to incredibly heat-less sex scenes this book had it all. It is a shamefully bad book.

So my question is, was Honeymoon an aberration, or is this guy a really poor excuse for a writer, and, if it is the later, why does anyone buy his books?