Heres my recomendation for the grudge problem. If they want to act all nice and friendly, just be nice and friendly, but tell them that you dont want them to stay with you, and to go away. People you do trust, you can be more willing to accept cohabitance.
I for one am not going to pretend that I trust anyone. I am going assume people want to kill, or steal, or grief, because thats all the people have shown. My definition of greifing does not match up with the servers definition, so forgive me if I use that word liberaly. Or don't forgive me, it makes little difference.
Those of you who say I am not making friends, can pack it. Every time Vlad and I are trusting or allow someone into the place, they raid and greif. there are trustworthy people, but they dont come around because they are huddling in their towns and dont socialize very much except for war or trade. People who are wandering around are more than likely raiders with the intent to kill you. Be paranoid, and be safe.