I think my worst case is just as 64-bit cpus were first emerging, i had a friend getting a new pc for gaming, hence i told him to get an AMD athlon. Another friend of mine said "wtf are you on about, intel all the way" to which I replied "well, ok, its debatable, but if you want my opinion, at this particular moment in time, amd's are better for gaming"
we then went into debating why for a good week afterwards, by which time this friend also decided he wanted a new pc, and fitted it with an intel, while the first friend took my advice and got an AMD.
now, when this guy was saying "get intel" i assumed he wasnt a complete idiot and was on about a pentium. at our next lan party, he turned up, after a month of boasting about how awesome his new intel cpu was, we observed him playing CS:S at like 10fps, wondered why.. the idiot had got a celeron..