I thought this was only a risk if using an improper client? So if I were to use a bitcoin cash wallet to send bitcoin cash, it should not send bitcoin gold by mistake, right (even if replay protection was not active)? And vice-versa.
It doesn't work that way. The whole point of a replay attack is that the same transaction is valid on two or more forks. Even if you were to use a "correct" client to send the Bitcoin Cash, the transaction may be valid on another fork. Anyone can then take the transaction and broadcast it on other forks. The recipients would be receiving more than one coin.
So is a lot of bitcoin gold being received erroneously by recipients then? I have not heard about anyone waiting to make bitcoin or bitcoin cash transactions because of the effect on bitcoin gold (until they implement replay protection).
Did the replay protection for bitcoin cash go bi-directionally? So that any coins sent on either of the 2 chains will not affect the other?
How could I check if any BTC/BCH I sent could be claimed as BTG by those recipients?