Not unkind, just adamant. We go through this same question, as you've already pointed out, quite often.
The bottom line is that there is no virus, no worm, and no malware that can affect OS X at this time. There have been the couple of trojans in the last year or so as I pointed out earlier.
All the newbies come back pointing out some article they have read saying they should run an A-V on their Mac. Time after time, these articles have either been written by an A-V company or sponsored by an A-V company. And all the virii, worms and malware they point to pre-date OS X and have not been seen in the wild in almost 10 years.
Seems it's easy for them to convince the long time windows users that their software is needed, when it couldn't be farther from the truth.
In the end, it's up to each individual. Believe the purveyors of the software that you need them, or believe the users of OS X that have been using their machines for years without that software.
One thing you'll notice on practically all Mac forums whether this one or another... those recommending an A-V typically have <50 posts, while those recommending against using one have >500 posts.
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@Bob
I read about something called "iServicestrojan" that is an actual trojan that went around that affected macs (apparently). Do you know of such a file?
And from my first post above:
There are (or were) a couple of DNS trojans being spread by pirated copies of Mac software and supposed video codec downloads on some p0rn sites. Stay away from both. Both also required that you enable them by entering your master password.