Naw,... It's more like the concert t-shirt OG rules. You don't wear a shirt advertising the same band that is playing unless that shirt is over 20 years old, and from a show you attended. If you're home mountain is X, it's fine to wear a shirt from Y as long as you actually went there and skied there. If it's a shirt with X, it has to be something really special, rare, like from a meltdown games there 20 years ago or whatever..