Can cheap hotend parts sourced from China actually produce good prints?
Hard to say for sure - my whole printer is cheap parts bought as a kit in China by a Chinese student who abandoned it in the US (I resurrected it after it was abandoned.) It includes all the parts you list, and I think we finally sorted out what the thermistor actually is so the temperatures are more accurate now.

It prints. 

Could it print better? - Probably, but at some point replacing all the various cheap parts starts to look foolish .vs. just build a new printer with better parts all around, leaving the original functional. I doubt I've ever met a "E3D V6" and I'd have to google it to see what sort of paragon of printing it's supposed to be. The only thing I'm actually considering replacing is the nozzle itself, partly because I'm just guessing what size it is (mostly based on the way it prints when set to various sizes.) I'm also contemplating adding some sort of insulation for the heater block, having squnched some aluminum foil around it as a first stop-gap.

Likewise, if your concern is with burrs, etc. a degree of fettling by you can sort that sort of thing out, if you know to do it and how to do it (i.e. you need to be somewhat mechanically ept.) But of course "parts from China" are not a monolithic entity - there are good parts and bad parts that both come from China - given the state of internet sales, you may well have (unknown to you) the choice of parts that passed quality control, parts that failed quality control, and parts that quality control never looked at (some of which might pass, some of which might fail), from the same production facility, available to you from various vendors at various price points. And then there are many different production facilities as well.

Production in the US or Europe is no magic bullet either - competing with imports on price is difficult, so one hopes that superior quality is on offer, but it may or may not actually be from a given vendor, or a given batch of parts.