"It's one thing to leave negative feedback without given the other person a chance to correct any problems you have but when you do try to communicate and they ignore and you see them logging in every day so you know they aren't dead... that's when negative is justified."
Agreed. I don't think it's 'childish' to leave negative feedback if it looks like the other person is willfully not communicating while logging in every day. I think it's important to give warning to other members on the website when dealing with certain members so that they don't get the same runaround. In this particular case I think at the very best it's a neutral feedback if you don't care so much about the cards that you never got. If you think you just got fleeced then it's a negative for sure, if only to save others from the hassle.
The tricky situation is when someone doesn't communicate, then bails on the site by not logging in, so you have no idea if something happened to them or if they just took the cards and ran. A neutral feedback would at least give people an idea of what happened so that, if the member returns to the site, they don't get to come back as if nothing happened.
As much as I would like to trust everyone here and keep things fun, I think it's important to work together as a community to try and make the trading aspect of the site as honest as possible by providing truthful feedback.