Google shows different search results for different computers based on the IP Address of the computer. So a visitor in US is likely to see a different set of websites for “buy flowers” than someone in Italy or Australia.
Matt suggest adding the gl parameter to your Google Search queries with the ISO code of the country. For example, google.com/search?q=bank&gl=us searches as if you’re in the U.S., and returns Bank of America at #1. But google.com/search?q=bank&gl=uk does the search as if you’re in the UK, and returns Lloyds TSB at #1.
The ISO country codes can be grabbed from the Google Adsense Sandbox.