Google’s head of search spam, Matt Cutts announced in a video that Google fights search spam at an international level but does tend to have a stronger spam fighting sense in the Google.com, English search results.
Matt Cutts explained that with most of Google’s spam fighting algorithms, such as the Panda and Penguin algorithms, Google does put a lot of effort into internationalizing them. This way the algorithms don’t just work on English search results but all search results.
Google does indeed sometimes launch algorithms just for the English language but when possible, Google does try to launch them globally.
Matt Cutts added that they have Googlers around the world who work in search quality fighting spam on a manual level in 40 or so different languages.
Here is the video: