Indeed, this seems to be what has happened to my site. The nature of our business means that many products do read similarly to a spider, when in real life they are totally different and cannot be included all as one product. I now have hundreds of pages in the Index which have no descriptions, I've lost a notch of PR and our site is filtered for the major KW's applicable, presumably some kind of penalty.
Also, how do you disallow G from product pages which are created dynamically from templates? Apart from disallowing for all product pages?