Hi guys,
as a programmer here at Avast who does not deal with viruses I sometimes go upstairs to the virus lab and I am amazed. I especially love the charts the virus guys there have with their samples and colors, green means avast is the winner on all the samples received on that day.
There is also a large group of samples that avast detect exclusively, meaning that so far no other antivirus we know of is detecting it.
I sometimes wonder why isn't Avast the by far leader in all test if we have so much samples that only avast detects and no other competitor (not sure if Comodo is even tested).
My guess is that other antivirus's virus labs have also similar charts with similar yet differt sample sets. And this is probably the reason why the testing should be done by some independend well respected organization or person, who knows how to choose the test sets in an unbiased way - or at least tries to do so or holds an open discussion about the way how to do it.