Not much annoys me, but when someone says that "Fender is my guitar, they're the best thing I've ever played, and ever will", yet they have never bothered to play any other bass (or guitars alike), it really gets on my nut!
If someone genuinly loves Fender for what it is, and have played many other instruments and settled on Fender as their comfortable instrument, then I think it's great because Fender are impacting people in a way that instruments are meant to.