At the bottom of every search results page is a link that says something like "give us feedback". That's your first point of call for reporting bad results, spam, etc.
If you have a whole bunch queries that are somehow related, like say we do a bad job at Python function names, then you can collect them and post them on our forums in one go.
And please give us details as Matt said. In particular, If your refer to a specific result, please say its URL not "5th result" because rankings fluctuate.
