I'm not mindlessly loyal to anyone, thats how bad purchases get made. Its also how bad companies do bad things to people for years at a time. Having said that, theres a few brands that have done so well over the years they are entitled to a mistake or two and still may get my support.
Toyota, ignoring their Scion line. ATI. HP (only for printers and monitors). Phillips, mostly just for CRT's, I know nothing of their LCD's. Sony for general stuff, even though they are overpriced. Coke. New Coke was not so bad I couldnt get over it. Nintendo, even though they've been progressively pissing me off after the SNES. For the same reasons, Square-Enix.
And finally, the most important: Willy Wonka.