I never send first in a trade unless that person has more positives than me, and if there are any negatives, they ship first or no deal. The positive ratings have to be as a seller or trader; I love when people point out there multiple positive rating, and it is all as a buyer lol, that says nothing for their integrity.
Sorry to hear you did a deal with a pos, I am fortunate most of the people I have dealt with have been pretty good.