Ppl are already talking about htis in various posts, but this one is more populated, look for "Muted" post, for some reason "the site protects itself" so well that it doesn't let me post its own link Smart design, huh!
Spam is very common in private chats. Users are automatically protected by the system from spammers and scammers in public as well as private conversations. All mutes are triggered by spam/scam phrases or certain URL's.