We are about to remove 1000's of products from our ecommerce store and most of these pages are currently indexed by Google. The potential problem I see is that these pages are dynamically created and if the product no longer exists the shopping cart script displays a standard "product not found" message (not a true 404 error). This would mean that we would have 1000's of pages with the exact same content for GoogleBot to read (i.e. the "product not found" pages).
Will Google just naturally drop these pages from the index (which would be great), or will Google think we are trying to spam them with 1000's of identical pages? Any feedback is appreciated.
Thanks!