I know some people who are into splogging a lot, and they do make money, I'm not saying that it doesn't work, I know it works. The main problem they have though is that google is dropping their sites. That doesn't mean that the sites stop making any money at all, because Yahoo and MSN are known to drop them much later or not at all.
I'm not sure what gets them dropped or not dropped exactly because I haven't tried it myself but this is what I do know;
-coop can get you banned
-pinging all your articles every minute can get you banned
-using rss submitters and pingbacks so intensively that you're getting 5000+ links the first day can get people banned
-leaving footprints in splog software default templates gets you banned