Hmm.
I guess it depends on the model and what you perceive as 'passable'. For one, I do not wish to put any money down for a plywood guitar or an instrument of inferior make whose manufacturer's goal is to 'emulate' an existing model.
However I must say that I own a TGM ovation copy which sounds pretty sweet (if not why I hold on to it for close to 3 years already?).
Not all 'copy' guitars are rubbish, but they are only meant to target those with a limited budget, and offer you the relevent performance for their price. And only once in a blue moon you get that one guitar which came off the production line that sounds great.
But you'd have to be pretty alert to such things because you'd be getting a great axe for a fook-tastic price. Most of the time it boils down to luck.