I've had decent luck with them, but I only buy the ones that are highly reviewed on Amazon. I've had a few that had issues out of the box when I bought them off ebay.
The engine has 7 hours on it, was it rebuilt? If it's been apart I would definitely check the timing and the valve clearances. I've had issues with both of the above when someone has brought me an engine that has been apart before but is extremely hard to tune.I've had lesser luck with a China carb for my Tecumseh 8.5hp snowblower. Been fighting carb issues with the thing since a friend gave it to me. Decided to try one since it was only $10 with free 2 day Prime shipping from Amazon. It did work, but not much better than the original one. Took me a good 1/2 an hour to tune it, and before you ask I do know how to tune a small engine carb. It will run well enough to blow snow, so that's all I'm worried about. There's tons of metal coming out of the oil, so I can only guess the camshaft is eating itself. Not the first time I've seen it happen. It's a shame as the engine has about 7 hours on it. I'll run it till it blows as he eventual plan is to put on a 13HP Predator.
The engine has 7 hours on it, was it rebuilt? If it's been apart I would definitely check the timing and the valve clearances. I've had issues with both of the above when someone has brought me an engine that has been apart before but is extremely hard to tune.