Hard woods make better driftwood... so if you can identify the type of wood it is that would help a ton. Otherwise use the old fingernail trick (poke your fingernail into the wood, hold your tongue securely between your top lip and front tooth and make your best guess to the hardness of the wood).
After the wood has been submerged for a few months higher grade wood will not flake off creating debris in the tank (but by this time you've already bought the wood...)
It's also silly to believe that driftwood from a particular country is good/bad wood, as I would guess that most if not all countries have more than one kind of tree. Both my best and my worst pieces of driftwood were bought as "Malaysian".