I wonder... would it be a ToS violation to accept one of those random FC invites, only to proceed straight to the FC chest and, permissions allowing, dump a bunch of useless loot into it?

"Just blacklist me!" Yeah? Well how about you blacklist 47 stacks of beastkin blood and bat wings?!

Petty, sure, but it's a minor thing to clean up and what one should expect from spamming invites anyway.