Agreed to what you say. Product quality and reliability in protection and performance will rise and fall through the years.I think that some people don't take a liking to some vendors doing better than their own preference, it has always been like this... Fact of the matter is that these testing companies pour so much work into testing professionally and conducting re-assessments prior to publishing the results. The results are based on fact... Product X detected X amount of samples, Product X blocked X amount of malicious links, Product X was light on resources or not under that testing environment, etc.
It doesn't mean a product is bad if it scores low and it doesn't mean a high scoring product always will score highly. It is just a test conducted by experienced people who are good with testing. Every vendor has good and bad days. Just because the results are factual doesn't mean they shouldn't be taken with a grain of salt and anyway these companies usually leave notes actually stating that 100% detection isn't always, just for their tests if it happens. We already know 100% of proper malware classification is impossible, the closest to that is blacklisted everything and allowing only the whitelisted (and then come file-less attacks from zero-day exploits from the web -> next big thing to overstepping the mark on that concept)
So also for what you said, I don't think it is weird that Tencent or VIPRE performed well in the test. Tomorrow? Maybe not so well. Its a hit and miss game with security software and malicious samples/website detection.
However, if the same product is being tested by the various labs and its standing is within the top 3 for the past 3 years then you can safely say the product has consistent quality and reliability in its protection and performance.
This is one of the ways to select a security product. Other ways will need to see the testing results at MT forums, read and get feedback from forums etc