As I read Pro CSS Technique, one point I am very interested in is "Avoiding Nonstructural Tags like Div and Span". Then I just realize that if my site contains more than two hundreds Divs and Spans per page; how does the Search Engine Crawler suffer from those and how does it index my pages?
It's not about search engine crawler suffering about those elements. It's that those elements don't have semantical value like many other elements have. So if you have paragraph of text, use <p>, use lists for marking up lists etc. Basically it's all about using element with suitable semantical meaning for that certain piece of mark up. For Divs and Spans, use those for mainly as extra containers for styling purposes.
I looked over the preview and from the sounds of it all the author is trying to say is to use the tag that is most appropriate for the content it contains. If you have a line of text that is your page header and you want it to look a specific way, place it in a styled H1/H2/H3 tag rather than just a span or div with the same style markup. By using the correct tags to describe your content it makes it much easier for the search engine to properly index and organize what it finds.
It's perfectly alright to have "over two hundred divs and spans" so long as the content they surround is intended for a div or span. It's all about semantics.
Ahh... Now I think i know something related to what you are talking about, some search algorithms will give more value to the pages content based on the content vs. non-content on the page, like how much is markup, and what percentage of that is text inside those nodes that shows up on the page.
They call the over-using of div's and span's "divitis". Search for it and you'll find a bunch of interesting articles on this subject :)
A good one: http://csscreator.com/?q=divitis