Since there are no "Mac virusses" out in the wild, there are no definition files - so no anti virus program can use those. They normally use Windows virus definition files, which will prevent you from spreading Windows virusses via email.
its never on
It doesn't load itself on boot and run in the background?
I guess my only concern is that there is a separate uninstaller for the software engine which makes it sound like it is obtrusive and really hooks into a base level of the OS. No?
Uninstaller? Are you talking about Windows here? None of what you are saying has relevance to OS X.
Uninstaller? Are you talking about Windows here? None of what you are saying has relevance to OS X.
ClamXav is designed to be run on a schedule, as well as having the option of scanning downloaded files (I believe, haven't used it).
I have ClamXav, but mine's never on. Don't worry, you can set it up so it won't be bothering you unless you want it too.