[Now Eley was trying to match Spock's description to the things he might have said to the Spirit. Had he ever said anything he could call 'sarcastic'? Could he even identify it if he did? Mocking someone did not seem to be something the recipient should find amusing...]

I am not sure if I do either... Your explanation does not sound like something I would say could contribute to amusement. Could it be that I do not understand 'irony' in that case?