I did not use any anti-virus software for years. I do irregular scans with tools like Spybot S&D and I am pretty sure that I am still virus-free. That might be due to the fact that I am a programmer and know what is suspicious.
Well, I'm not an expert at AV softwares, but I don't consider them useless, since the anti virus in my machine has helped protecting my system from many malwares. I'm quite satisfied my AV software performance. I'm using Avira Free. It does give false positives at times, but if I've doubt I check it with virustotal dot com.
For the last many year, I've never used my PC without any anti virus software.
Yes, I didn't mean to say that AV's are useless or that you shouldn't be using one - quite the opposite. They are definitely necessary. This is just to note that the industry in general has lagged seriously in "keeping up with the bad guys", serving up more marketing hype than real results and therefore one has to be doubly cautious.
Anti-virus software is useless crapware. Only unsafe operating systems built by morons with no technical skillz (ie. windows and such) even require such bandaid-solutions. Real operating systems don't need AV software.
Even the free AV softwares are less than useful. They gives tons of false positives, and because this makes them seem more useful, like they're actually doing something, the maintainers have no incentive whatsoever to fix this behaviour. Most don't even accept false-positive reports. Interesting thing is, that the false positives always only happen on software made by small, independent developers or small software companies. That's because the AV people know that the bigger software corporations have so much legal firepower that if they showed false positives on their software, they'd be in trouble. So the people who end up suffering from this immoral behaviour of AV software makers are the small, independent developers of software, while the big software houses don't care, and the AV companies keep making money out of fear-mongering.