Recently, I used a wet tissue to wipe off the dirt and sweat from my Split Spades. But after drying, the cards became very rough and simply can't be fanned.

I don't understand why cos I have used wet tissues on my Bikes before but there was no problem.

Anybody can provide a solution or provide an explanation?

I suggest that you apply some fanning powder to 'fix' the deck.

maybe the card absorb the moisture in the tissure.
try applying fanning powder.

IF it is bike cards you are talking about, I think it is pretty normal. This is because bike cards tend to bend or turn soft when exposed to water or moisture in this case. Yeah....fanning power might help

get another similiar deck, do a little bit of work (can't say what, it'll be exposure) and you'll have a Invisible/Brainwave deck ..LOL