I find it hard to believe that many people are not aware of botnets,
and what they are doing.  Of course, I’m so deep in technology and
the Internet that my “common sense” is now severely distorted. 
For those people who have not heard about botnets, this Washington Post botnet article is a great place to start.  It’s an eye opener.

When you read this article, just realize that this is about the botnets
that have been discovered and are known.  There are more out there
that are unknown, and the sizes of some of these botnets is staggering.  Read here, here, or here, about the FBI arrest of a many running a 400,000+ node botnet!  Oh yeah … and he was 20 years old.