I have Google Custom Search on my site (info on / selling aerials, poles, brackets, and clamps), it`s always been the free version, i.e. the one where sponsored adverts come up at the top of the listing. It`s been like that for years but just recently it has begun to concern me how many sales we could be losing with all these adverts for competitors products coming up on the search window. At first I wondered how much it`d cost to get the paid for version without the adverts, though finding that out isn`t actually easy, more and more companies don`t have phone numbers these days..... But, possibly more importantly, it also occurred to me that the fact Google can put their adverts on their search results off your site might improve your site`s ranking, is there any evidence for this theory ?