Use the Forum Jump menu below. That lists all the forum sections.

http://www.gnutellaforums.com/welcom...tml#post333116 click on blue link

As for your question, it's a matter of learning to recognise spammed junk, and yes, that may take a little time. The example images shown in that link I gave earlier gives a good starting point. You may also wish to add certain words to your keyword filter, check Direct instructions to eliminate porn from results & the sub-link provided in that post points to 'other' types of spam it can help remove from search results.