I'm writing this as I've seen a "don't buy from Hong Kong" guide.
I've purchased several watches, watch tools and other items from HK. My overwhelming experience has been positive. One automatic watch I bought broke 2 days after leaving positive feedback for the seller. I contacted the seller who was very apologetic and said he would send a replacement. "yeah, right" I thought, but he was good to his word and sent one out promptly.
Another time I bought my daughter a watch from another seller. they contacted me after a couple of weeks to ask why I hadn't left any feedback. I replied I hadn't received the watch, so they too said they would send a replacement and they did.
The only time something has failed to turn up totally was a jewellers loupe that I never received nor got my money back for.
Yes, there are sharks out there waiting to rip us off, but they're not just in HK. Maybe I've been very lucky, but I've bought from lots of different sellers over there and 99% of them have been honest people.
Buying on eBay will always have an element of risk, especially long distance, when there can be a language barrier too. One piece of advice I would give is to go onto toolhaus.org, enter the sellers ID and check all their neg feedback and let that help you make up your mind whether to buy from them or not.
In conclusion, I've mainly had good experiences buying from HK, it can be chancy, you can be ripped off, but doesn't that apply to any country?