I use three companies: Webroot, McAfee, and Lavasoft.
I don't want ANY spyware, adware, or anything else that I didn't deliberately install or agree, in some way, to have installed. I pay all three of these companies a fee to scan for and remove ALL of this crap, not most of it. If I find out that one of these companies is taking money to "delist" somebody, I will request my money back.
I'm using the Webroot now (Spysweeper). I like it so far. Dumped Norton off and just use AVG free.
I've got 4 computers in the house and 2 kids. If there's something bad out there, they will find it. :-)
So far so good with the Webroot. Haven't had anything bad happen since I installed it. I was using PC Safe but it let me down, so I went with Webroot on a friends recommendation.
Too bad there ain't a magic bullet for all of it. The guy who comes up with that is going to be rich.