I'd consider myself as hypocrite, two faced, changes stance depending on personal pre conceptions, and a bit of a tit all round 
I'm somewhere between.
I'll write off certain things without even trying them. Perhaps not completely dismiss them having any effect, but certainly that some things can make the huge changes often claimed. And also I feel many are far too overpriced.
I feel the "can't be measured" and "why bother, jus trust your ears" is over used. And when "proof" is being asked for, it can seem a bit of a cop out!
Ultimately though. I trust my ears. I've not done much cable or such experimenting. Simply replaced the freebies with something of apparant reasonable quality at reasonable cost.
My hearing may turn out to be poor. My system may be too shit to show up the benefits/weaknesses......... but it's my ears, and my system.
I respect other peoples beliefs and findings.
But that doesn't stop me thinking they may be a little delusional sometimes. :MILD:
It's been said that to "not" hear a difference, could be imagined just as much as hearing ones which aren't there. Possibly, but I think the pressure from hifi rags, and forums like this is generally far heavier toward telling people the *should* hear them than not.
I guess if I hear it (and am sure I really heard), that's all the proof I need. But if someone else is telling me they heard it, and it's a little far fetched..... well must be bollox 