Here is one from a visit to a hi-fi dealer a few weeks back. He was telling me about his new fuses which make a startling difference to the sound. I asked him whether he would like to give me a demonstration and compare a normal fuse to his expensive ($500!!!) fuse. He demurred - because apparently the $500 fuse is larger than a normal fuse, and it is fragile. He broke one when he was trying to remove it. I asked him why should I pay $500 for a bit of glass and wire, which is so poorly engineered that they did not make it a standard size and more robust? I mean, even many subjectivists are skeptical about magic fuses and they would demand a demonstration. And no demonstration = no sale. I wanted to be polite with him and said that if I don't get to evaluate the difference with my own ears, there is no way I would pay so much money for a fuse. Rather than my real reason, which would be too impolite to say aloud to such a nice guy.