At work we have McAfee. The only "viruses" it seems to detect are .exe files or .exe files in a .zip as attachments to e-mail, usually when the recipient needs them. Esay to get round by renaming the attachment as it's based on simple filename rules. We've had one infection in 10 years and that was because the AV software is *always* playing catch- up with the virus writers.
At home I don't run AV routinely. Occasionally I've tried the free trial version of well known brands and found absolutely nothing.
If you can scrae enough people you can make a lot of money.
MBQ