Mystical poor results on ppc campaign

in running my ecommerce site my biggest frustration with keywords/ppc/etc.etc is this...

an example:
I have a book, "the joys of XYZ" - I know the book is hard to find. I know with keyword tools that it IS being searched for.

I run a ppc campaign (adwords) featuring "the joys of XYZ" when the phrase is searched for. my ad is displayed (#1 position) ... but hardly ever clicked on.

I ask myself... OK... people are searching on the title of this book. They MUST be looking for this particular item... I present the item to them in my ad (with what I think is good copy) and they don't bite...

I just don't get it.....

amazon.com appears below my ad.. Is it possible people are just going with the "big name"??? Is it possible my copy isn't as good as I think? (I'll try other ads). Do people just IGNORE ppc advertising...

I wish there was a magical tool which told WHY a person was using a particular keyword. They may be looking for a book.. but WHY? To buy, compare, to simply see if still printed, to put under a table leg, etc, etc, etc.

frustrated and and in a quandry.....