Yes learning to recognise spam helps. Here's a help in hand in seeing typical spam sizes to beware of: http://www.gnutellaforums.com/335326-post2.html

Basically, ignore files less than 2,000 KB (2 MB) since no practical file will be smaller than 1,000 KB unless it's a simple document or image.

This might be some help too: http://www.gnutellaforums.com/search...tml#post335323