With the mudman series watches, including the GX56 Kings, they have a resin plate attached to the back, see the pictures below:
When I open up my King GXW56 today, I saw moisture under the back plate and possible also under the buttons (not 100% sure). So I realise that water can enter under the back plate, and be attracted there cause it's hard for it to evaporate. Imaging you are going into the poor with your watch, quit some amount of water will be attracted under the back plate.
Then my concern is that water can potentially be attracted under the mud-resistant buttons, long after you thought you watch is dry. Not knowing it, you do a lot of button operation, is it possible that water may enter into the module when you pushing buttons back and forth, thus bringing moisture even some amount of water into the module?
The way I see it, there is no water resistance at all when you push buttons. Probably that's why Casio stopped advising using the buttons under water, and even do not advise using it for frogmans (absurd)! Observe the picture below, there is no water resistance structure in the button pushing pins:
Then finally, my questions for you all, have you heard, saw or witnessed any g-shock start having moistures or even waters inside of the module after using its buttons under water? Are you concerned about this issue?