It's hard to say. You really need to look at seller 's feedback. Those three countries are growing up become one of the top country that buying luxury products, but again most if the fakes are made from there as well. Especially China.
Always authenticate!!!! I read sellers feedback but 100% is no indication of whether to trust a seller. I've had really good experiences with Japan sellers, and have communicated with Hong Kong ones aswell.
When my MIL went to HK a few months ago, she bought pre-loved LVs at this store that said that they only source their pre-loved bags from Japan because the products are always clean, good condition, and guaranteed authentic. I don't see any reason to be suspicious about the seller's products as long as they have good feedback and you have the bag authenticated here.
Check feedback and of course read the description carefully. LVs are sold all over the world. Because of the humid climate in the Asian locations, some (not all) bags that are stored improperly by their owners will have smells or odors primarily of mildew (sweetish smell but also pungent). Just a heads up, if seller indicates any kind of odor, I'd stay away.
Many people in Japan/Hong Kong make a good living, but their homes are tiny. So it's common for them to buy one or two luxury bags instead of ten lower-priced ones simply because of lack of space. I wouldn't question their authenticity any more than from anywhere else (but of course, always authenticate and check feedback!). However, as the above poster mentioned, anywhere that is hot and humid and doesn't have air conditioning can make bags/clothes smell musty/mildewy so that is something to watch out for.
I think no matter where you buy (except the Louis Vuitton) store, you'll have to be cautious. As long as you have it authenticated here on TPF, you will be fine keeping in mind the seller's reputation as well.