The nearest thing to a resolution offered so far is the "web of trust", offered by a more constructive poster than yourself earlier in this thread.
It isn't that much different from "real-world". There are tons of services where you pay in advance because you trust the other party as you know that it would hurt their reputation too much too just walk away with the customer's money.
This works even better in case of a repeated contract: For example if an online service with a subscription of 3$/month suddenly stops giving value for your money, you just stop renewing and they loose a customer. You know that, they know that, they know that you know it... etc ad infinitum. And things keep going smoothly.
I am not saying that what I wrote solves all the problems (one-time contracts such as ebay is a different story), but this argument itself does not prove that bitcoins are worthless.
Yeah, but a key element to Bitcoin is anonymity. Building trust with an anonymous counterparty is tricky.
The "web of trust" seems to address this quite well and also remain decentralised and hence outside easy regulation/control.
But I suspect it is still subject to subversion and this is the danger.