One way to avoid this problem is to NOT download anything smaller than 2000kb.
You should know that most songs are larger than 277kb. I would say the average audio file is somewhere in the range of 3000kb to 6000kb depending on the bitrate.
Another indication to leave the file alone is if there is no bitrate.
Also try filtering out the following file extensions for a much better search result. .wma, .exe, .rar, .html, .com, .zip, .mov. Go to Tools > Options > Filters > Keywords. After you put the extensions in to block, hit apply and then OK. This will clean up a ton of crap. Also see link below
This thread is long but it has some helpful info.
Junk Filter
Hope this helps..