Hogarth Ferguson
Well-known
This pretty much applies to sellers from any region.
I've had nothing but good experiences from Japanese sellers, including some under-rated bargains, but then again, it's important to pick the right sellers...no matter where they are from.
It's not all that difficult.
I think the only reason this thread is about Japanese sellers and not everyone is, because of the prevalence of camera equipment coming from Japan.
I generally don't buy from ebay anymore, I prefer to deal with Bellamy. Sure, he has fees and higher prices, but I trust him and he has been great to deal with.