I if can answer cookiemonster's question, I would say if "men in white coats" could 'prove' cables sound different in a double blind test (let me just duck my head for mentioning b***d testing) then I would accept that if I couldn't hear a difference that either my ears or my hi-fi weren't good enough. I think most sensible people would too. After all, people who are colour blind can't distinguish between some shades of red and green but I doubt they think that this means these colours aren't different.
I can understand why Robbo had his rant about blind testing. But a couple of points. I think people who, like me, are less experinced in hi-fi read the forums/newsgroups for advice and ideas from those more experienced. Unfortunately (because it is tedious) or fortunately (because it may save me money) this means 'finding out' about all this blind testing stuff. It has made me question just how different cables, CD players etc. are and if claims of massive improvements do really exist. In fact, it has made me very sceptical about much of hi-fi in general.
I was quite suprised to learn that blind tests were not used/supported by people to prove that they can hear differences but rather it seems invariably they are used by sceptics to disprove differences. As wolfgang says, in wine tasting it is the other way round.
I don't think it's up to forum members to prove this. As pointed out this is just a hobby for us. But I would just like a magazine, say, with experienced, full-time hi-fi reviewers to at least attempt some genuine blind tests with cables (even if one is £10,000 and one is £10) and draw some decent conclusions. And if said blind test were to show reviewer X could reliably distinguish between 2 cables then I think cable 'believers' would certainly change their minds about the usefullness of blind tests and this would be great (the best?) evidence to use against the 'cables sound no different' crowd.
Personally, I should add that I used to believe I heard differences in cables (though only subtle ones but I was using reasonably cheap cables and my system is a long way from hi-end) but, since doubting that this is possible, now I don't hear differences. I think it is only fair that people have both sides and can decide for themselves and this may mean some hard truths for both sides e.g. some people may be imagining differences, some peoples ears/hi-fi may simply not be good enough.