Why is google displaying MORE results if you EXCLUDE additional words trying to slim down the results?

Example:





Google: torrent paris: 290,000 hits.


Google: torrent paris -wallpaper: 2,160,000 hits





I see this very often when trying to slim down the number of search results. Often, the opposite effect is the result.


Obviously, Google does something wrong when searching it's databases. But what?

Why is google displaying MORE results if you EXCLUDE additional words trying to slim down the results?
The more words there are, the more possible sites there are to have 1 of those words somewhere in the site. I'm assuming that most of those only have one of those words listed once on the site.
Reply:Enter your search term. click search. On the first results page, scroll all the way down and click 'search within results' Towards the lower left. Enter a second, narrowing term. hit the enter key.