There's people who claim to be able to tell the difference between high quality $200 cables and the off-the-net $20 ones.
I call these people freaks and promptly dismiss them-they're often the same ones who feel it's worth it to spend $20K on a sound system while they're living in a one-bedroom apartment with their two kids. (OK, OK, the guy I'm thinking of had a two bedroom place, but still).