Most autoblogs get their traffic from trackbacks and pinging. If you're going to do it en masse (which is the only real way to make money off of them), then you shouldn't worry too much about getting indexed. Just get some cheap .infos and spam the hell out of them. Even if your sites managed to get indexed, its more than likely you'll be getting angry emails and DMCAs from the original publishers. That's why
Eli recommends keeping them for only a couple of weeks.