What sounds unethical to me is incredibly one sided abusive contracts that are incredibly difficult to cancel, even with agreed upon terms.
It sounds perfectly ethical to me. "I don't want to pay for goods and services I don't want to receive anymore". This is an idea that has been tested many many times in US case law, and therefore sounds perfectly legal as well.
What sounds unethical to me is incredibly one sided abusive contracts that are incredibly difficult to cancel, even with agreed upon terms.
Nothing in the description on the site implied a one-sided, abusive contract. There is nothing inherently one-sided or abusive about either an ongoing subscription or a service that offers a free trial but automatically starts charging at the end of the trial period if you don't cancel.
Obviously if the charging organisation is misleading it's a different matter, whether that was hiding or being deceptive about what would really be charged or offering a trial but then creating barriers to permitted cancellation. I don't know about the US, but here in Europe there are now some very one-sided (pro-consumer) rules about this kind of thing.
However, if the deal was legit, knowingly using a card that won't stand up and thus avoiding payments genuinely due is fraud, pure and simple.
It sounds perfectly ethical to me. "I don't want to pay for goods and services I don't want to receive anymore". This is an idea that has been tested many many times in US case law, and therefore sounds perfectly legal as well.