> Try searching for "caravan" in a query not related to buying caravans, or caravan holiday parks (I was searching for a particular book that featured a caravan)
http://m.bitraf.no/~mortehu/skrot/caravan_book.png
It even shows the cover of several books featuring a caravan.
Google is absolutely unusable for some search terms that are not part of the primary association of the term. Try searching for "caravan" in a query not related to buying caravans, or caravan holiday parks (I was searching for a particular book that featured a caravan). If I don't mention the word "buy" or "holiday" I would not expect to see either.