I have a card with $0 on it for this purpose. Services count on you forgetting to cancel instead of you liking the product per se. If I like it I change the card, but most products I don’t so they bounce. Works well.
Aren't most payment systems making a $1 or $0.1 block/charge to confirm the card is real and has non-zero balance? At least that is my experience as an European user, whenever I try to subscribe to anything that came out of the US.
