duh! Did you look thru the stickies in the forum before posting? Any file that's under 1,000 KB you select in the search results & press the Junk filter button which has the trash can icon. It's a dynamic learning filter so you need to train it. It takes time but does work.
Also you might want to see these links
Direct instructions to eliminate porn from results & also this one
autogenerated spam results ____ / ____
autogenerated mp3 spam results