Google's Matt Cutts said Google does indeed fight spam at a global level both algorithmically and manually.
In a recent video, Matt said they have Googlers who fight spam manually in over 40 different languages and regions. He added that with most of their algorithms, they do their best to make sure they work in all languages and not just English.
Google's Matt Cutts did admit that English language queries in Google.com do get more attention because (1) there are more searchers there and (2) there are more engineers who speak the language and use Google.com.
Here is the video:
Forum discussion at Google+.