That's the thing with all tests in general. It's always about understanding the test, what its trying to accomplish/show. No test is perfect and it's important to understand the potential weaknesses of said tests. The problem is though, rarely, if ever do most people understand what's truly going on. All people do is focus on the total numbers, or which product has the most green on a graph. People constantly jump ship because of this. Take the HUB for example, no one really looks at the overall number of detections/blocks the product got. All they look at is the infection status of the system and just assume that if a program cant always keep a system infection free than its garbage.
It's the same with any test, most people dont take the time to understand them, they just make assumptions/decisions based on the totals.