Feliks :
ssddx :
since this is posted in cpus i am guessing you are referring to amd vs intel fanboyism. while there are certainly benchmarks which absolutely prove one way or the other which is superior for what budget level and specific task there will always be people who have the opposite opinion despite things proven otherwise or who try and generalize one way or the other.
Actually (didn't mean this to post in CPUs), I'm referring to several fanboyisms. PSU fanboyisms, GPU Fanboyisms (Nvidia vs AMD), CPU Fanboyisms (AMD vs Intel), etc. There's fanboyisms almost everywhere you look x) One of the most notable I've actually seen though are the PSU ones.
There are certainly fans of products but that is rare to see when you would get a suggestion just because of a brand, unless it's a general statement about a known quality of a brand. In PSU you have some generally highly regarded brands like PC Power and Cooling (for old school users), EVGA, Silverstone, Antec, brands like that, while other brands are known for poorer quality. So instead of trying to find one of 30 product numbers you can see someone just saying "pick an EVGA power supply over a Corsair" in general, and they would be correct in most situations.
After a while you pick up an awareness of products in categories and what brand is good in what price range. To use speakers as an example, I know that in the higher end, Logitech is as good as any, their THX rated speakers are excellent and have always gotten high reviews. In the lower end, under $50, there are quite a few brands about as good however so that is not a go-to pick there, but in general Logitech is a known quantity. So without going into things like Bose, Klipsh, etc.. I can pretty much say "Logitech speakers are good" and be right most of the time, but in the lower end I may not just say that.