When I was a kid I thought any liquid on a cart period, would fry it, tossed my copy of Kirby's Adventure because somebody dumped juice in it. (Weirdly I had made some kind of mental exception for invulnerable GBC carts, which I regularly left outside.)
Later on when I found out that they only fry if running, i started "bathing" my carts I wanted clean by sloshing them through a tub of water, cleaning the connectors with TP, and then leaving them to dry in an AC duct.
Nowadays I just use q-tips and alcohol, and only for games that have been sitting long enough to collect grime or have just randomly stopped working.
Never put Nail Polish Remover on a game disc.