Absolutely. And I am not ashamed of it, either. A book's cover is (usually) a very deliberate choice by the publisher, and I think that it definitely is meant to be used as a means of swaying readers.
His chick lit example is perfect. I'm not a big fan of that genre, so if I see a cover with all the usual trappings I'll give it a miss without even a glance at the description.
I also tend to judge by size. I'm not a fan of mysteries or romance, so I usually give mass markets a miss.