When looking for music:

Files that have (*) after the filename, * being a number, in most cases are bad files. Sometimes (*) in front, but often just the number of the song on CD.

Most bad MP3-files are 128 kbps, higher bitrate tends to be clean, maybe because of longer downloadtime. The misfit likes their virus to be spread fast.

When looking for a popular song. Never search for both Artist and songname at the same time. Tends to bring up a lot of bad results