It only took me 2 searches to filter out the typical auto-spam such as mp3 spam & the other type of M_Y_S_E_A_R_C_H type of spam with the ipod adverts. The virii are harder to filter out ... needs a lot of persistence.
You need some references to work with. Here's some: 1.
autogenerated spam results, & also
2.
autogenerated mp3 spam results
3.
WARNING: Viruses on network you should be aware of! (click on link)
* ie: the spam filter will work with both the file size & the filename. As previously said, you need to train it bit by bit. Some spam is easier to filter out than others!