I totally agree that the point of beach books is to relax, but I have sympathy for being annoyed with a supposedly "relaxing" book that is just DUMB. I'd define a beach book, for myself, as somewhere in between brainless fluff (which will annoy me) and really dense, Intellectual stuff (Setanta's history books, or whatever.) I'd say something like "Me Talk Pretty One Day" (David Sedaris, hilarious) would fit the bill for me.
Is David Sedaris somehow connected with television mad woman Amy Sedaris?
There is some fluff that I love -- several movies like The Three Amigos or Eating Raoul or This is Spinal Tap -- come to mind. I panicked the young lady who worked at the video rental several years ago when I began watching movies like that: she didn't know what to make of someone old enough to be her mom watching them and at first tried to explain them to me. Then she reported me to her friends as "cool."
However, I find reading fluff anything but relaxing. Actually builds up tension.