i think pickup, electronics, etc can all be changed, but the real meat and bones of the guitar - the body, must be good.
some brands tend to be quite consistent about the build quality of their guitar bodies, especially MIJ guitars like ESP, Fender Japan and Ibanez MIJs. I find US brands are a little less consistent, both in build quality like 70s Gibsons and post-CBS Fenders, as well as in changes in design such as the large-heel PRS design. I think these are generally quite minor issues though, and overall US guitars are very good.
in general my order of preference is Japanese guitars, then US guitars, then Korean guitars, then anything else. ultimately though, bottom line is the body must be good, everything else can be changed.
i tried some ESP guitars yesterday and might i just say that between a US and Japanese version of the same model, both guitar bodies felt almost identical aside from the US one being in gloss finish and the Japanese one being a satin/matt finish. neck profile was identical. even the body weight was probably very close, though admittedly it's a little hard to gauge just by holding it.
that was pretty impressive. most guitar companies i know don't have such uniform build quality across different manufacturing countries. perhaps it was coincidence, i won't know till i am able to try more variants of the model from both US and Japan. but i have to say i was really quite impressed. as a side note, the electronics and hardware were all top notch, which was a plus.
but the body. seriously. try one, it's quite sexy.
