In my experience, the spam does not seem that much in relation to real posts.

heres the highest paying adsense terms

http://www.cwire.org/2006/03/23/updated-highest-paying-adsense-keywords/

yes groups are being spammed highly.. I opened a group [mesh06] and had to delete approx 8 postings that were spam. However, I must say that google algo flagged this as 'possible spam' – this makes me think that google as enough intelligence to recongize spam..however they are not in a position to negate the flow of new groups into public consupmtion ..

I have a question.. how do spammers know that a new group has been initated /created ?? what is google doing to spawn such information ??