I've set up the 'site-flavoured' option on my site, but I must confess I don't understand what practical difference it is going to make. If I have a site about blue widgets, and someone searches for widgets, will Google start returning search results as if the user had asked for blue widgets?
I've been finding the "site search" and "Adsense search" in general has not been working well. Unless I delete my publisher ID from the search request generated when initiating a site search; a search on my site, which should return all pages, only yields about half the pages. Many pages are missing from the results. Your visitors will not find many of your pages. Try some searches, perhaps for "quotes" in low level pages of your site, the pages will not be found by Adsense search, but they will be found by a "normal" Google search.
I have experimented with this on several large WW publishers sites and found exactly the same problems, many pages are not indexed when using "Adsense search". Your visitors may not find the topic they're looking for.
You can do some searches to test this, just DON'T CLICK ON THE ADS!
Now we have "Site flavored" search when "Site Search" doesn't work properly.
Perhaps this is why the Adsense BOT has been accused of do indexing, maybe it is, and not to well!