Looking through the newer freebies / Free Stuff here, I found a model that might have been useful.
After going through a serious malware situation recently, I scan incoming files.
This file contained Eblaster - spyware that "emails, chats, instant messages, web sites visited and keystrokes" as eblaster.com promises.
My assumption is that the inclusion of this spyware was unintended: but the file got deleted, anyway. I need a clean computer more than I need a freebie.
That experience got me curious, so I went back through every file I've gotten from Renderosity.
Of purchased items, zero files were infected.
On the other hand, over a dozen freebie *.zip files were infected with Eblaster. Bad news: the ones I haven't opened, I can't now. Not without violating my new protocols and common sense. Good news: I freed up about 11.2 megabytes on my hard drive.
The infected files were downloaded around October and November of 2008, but other files downloaded around the same time weren't infected. There didn't seem to be any pattern: one file from a vendor might be infected, another from the same vendor might not be.
I'm treating this as a learning experience: And thought others might benefit from what I found.
The software that picked up Eblaster was Spybot 1.6.0.