try buying a new one and do some research on the gag first. I have never had the problem but then I go for cock gags and not hard rubber ones. You may have just bought one that wasn't made for real use but a shady manufacturer or one that is supposed to taste bad for certain folks that want the gag to be an unpleasant experience.

try to avoid the harder rubbers ones they should be hardest to rid of taste go with the new flesh style material.