If you browse a few of the home shop machinist sites, you will understand what can be wrong with mainland (communisit) china made machinery.
To summarize:
1. The products are built to compete with Taiwan-made machine tools. To meet the price objectives, they have to cut corners on their "economy" lathes and mills, for example. The iron castings are not aged for stability. The metallurgy is questionable. Accuracy and repeatablity of settings can be acceptable, or it can be just lousy...depends on the particular specimen you get.
2. Spare parts availability may be a problem. You break a casting, a housing, or a lag screw, and replacements may not be available, PERIOD.
3. The top-of-the-line lathes and mills sold under the Grizzly and Enco brand names are fairly good. You notice that they sell "good" and better" levels of machines. They also do not handle the "economy" chinese models.
4. The cheapest models as sold at Harbor Freight are okay for casual hobby use, but most users have quickly discovered the shortcomings of an HF lathe or lathe/mill combo. Any trained machinist will point out the deficfiencies, namely: sloppy fit, lack of repeatibility, stability, and precision, and overly poor quality.
5. I've found that the bottom-end machines are primarily made in India and mainland China. ditto for tooling and accessories.
6. Please remember that Mainland China is a relative newcomer to the consumer market for powered machine tools. They are trying to compete with other countries that have decades, if not generations of experience in building power machine tools.
With these considerations in mind, I stand by my earlier statement that a hobbyist can do well by shopping carefully for good condition used American machines, or going directly to the better quality Taiwan-made lathes and mills.
HTH
John