Waves admin just banned NGR asset (niggercoin) from their "decentralised" exchange because it hurt someone's feelings. Not like I think it was great idea to promote such an asset on waves, yet it's not how this "decentralised" exchange supposed to work.
https://www.reddit.com/r/Wavesplatform/comments/6h15e5/waves_not_decentralised/
http://boards.4chan.org/biz/thread/2428429/wave-platform-cuts-ties-to-nigger-coins

Since waves claim they made "decentralised permissionless exchange" I think we can call it scam for now. Some people who "misbehave" will loose their money now.
It seems WAVES admins have full control over their exchange and can censor everything they want.