We have an 'infestation of the nastiest kind'. Well, at least some spyware on various machines. However, the spyware programs, despite covering 30-some-thousand spyware types, still don't get it all. And even then, they report having found some 50-instances of various spyware. I think not.
Obviously spyware apps want to make you feel good about using that app, so therefore they can easily be subject to self-inflating their reports to make you think, "Ah, what a good piece of software, I want to send them my paycheck and the kids' college fund. What does Johnny & Suzie need to go to college for, now that their usage isn't being tracked by big green Ad-Men."
In a good report, Eric Howes did a Anti-Spyware Test (Guide) that does a battery of tests against some 15 spyware apps. In the end? He suggests running several apps, since none of them are conclusive.
Another good resource is PC Pitstop Top 25 Spyware and Adware, which lists the top 25 'criminal cremenies'.
I doth say unto thee, I am glad I run a mac (though I doubt they're immune.)