FranklinTheCow1 messaged me; "Come in house for diamond" so i TPAd to him and he accepted it, but the very second i spawned, he put lava on me, and didnt let me go and as i was dead he took all my items i was holding and when i messaged him to give it back he didnt respond, and when i invited him to my house, he declined it, and he didnt even care, he didnt respond even though he saw my messages.
It's just common sense to not tp to people that say "free diamonds" or really good deals on items. No one is going to give their good items away for really cheap prices or free.
If you proof of this, report it via this link: http://itsjerryandharry.com/forums/scamming-griefing.32/
If someone says free heads/diamonds/stuff, tpa now! Then it is probally a killer. I always tpa with an empty inventory so I won't lose stuff and then I can report. So huge tip: never tpa to a stranger with items in your inventory.