We were on top of the mountain standing just off a steep drop and looking down into the valley below when a bird flew gracefully in front of our eyes.
"Wow! How I wish I could fly like that"
"Oh! Flying from here is a piece of cake. It is the landing that is the problem"
Huh! This 'Good one' as a reaction to a joke or a witticism always confuses me. I can still remember my long gone school days when I used to crack what I thought was a joke and be met with sepulchral silence. Then one of the guys would catch the pleading, pathetic look on my face and say, "Good one!" Now, when someone says "Good one" in response to a joke is it only sympathy that makes him say it instead of "Oh! Was that a joke?" or scratching his ribs with both hands (a throw-back gesture that reminds you of your Darwinian origins) and emitting a derisive "Ha Ha"?
There is an Asimov story - "Joker" or some such name - in which he says that the only jokes that people laugh at are ones that begin "Ever heard of this one before" or some such thing that ascribes an unknown origin to the joke. He claims that all the on-the-spot witticisms only beget groans or "Good One"s depending on the nature of the recipient. From which I conclude that Isaac Asimov too had had his share of jokes falling flat on unpromising soil or eliciting feeble "Good one"s.
Sometimes, it does feel like his theory is right. The "Good one" shoots out with such enthusiasm - and without the stimulus of pathos in the face - that it seems like it was meant. This, however, does not necessarily mean that the Wit can dance a saraband in happiness. It only means that, though the joke was not good enough to laugh at, it was good enough to be acknowledged.
Sometimes, though, it is the recipient of the witticism who needs the crutch of a "Good one". There are those unfortunate beings who actually cannot get a joke. When, however, they are acute enough to understand when the other person thinks that what he said is a joke (and it is not every Wit who is overwhelmed by his own humor that he conveniently goes "Ha Ha Ha" and gives you a clue), then he can come out with a "Good one" to cover up the fact that he was totally in the dark about what was funny about it.
In sum, a "Good One" is not a good enough one - at least for the recipient. If, perchance, you feel the pressing need to leave a "Good one" in the comments, you do it at the peril of my taking you for the third category of people above!