They have a way lower chance, because they look so different and are harder to fake, with all the paper wrapping etc.
When you find them you can be pretty sure they are not bootleg, if it's important to you that they are the Japanese versions, make sure they are befor you bid, some have Taiwanese and other overseas versions aswell. Also, remember that if they have damages they can often be pretty apparent as paper is a very weak material.
If it's stated to be from Japan, and the code is like AVDD-##### you can be pretty sure it's original
. I'm pretty sure that the copies I have from eBay are originals, but hey, if you didn't buy it in store when it was new, how could you possibly be 100% sure? hehe.
(yes, it's AVDD for the 3" ones)