as a general rule of thumb............... treat all sellers from China, Hong Kong ( except that flyboy Hizento dude )and SE Asia selling Japanese swords as potential " problem ".
Also bear in mind that in China there's a law banning export of antiquities ( punishable by death, usually a bullet to the head, family members pay for the bullet ), so when you see they are selling Ming vases, paintings with loads of imperial seals etc. etc., you have to ask yourself this question........ " would that dude be stupid enough to risk his/her life just so he/she can sell you a national treasure for 99 cents starting bid and 90 bucks EMS shipping ? ". If you think yes, why not ? THen may i have whatever you are smokin' ? it must be very good sh%$# !!
milt THE ronin