Ask HN: Stripe failed payments

I contacted stripe and looked at the help but didn't get any real answer, so I'm perplexed as to why people who enter their credit cards for a 14-day trial, the payment fails every single time.

Are they using one time credit cards or doing something on their end?

Won't getting failed charges hurt their credit rating? Wouldn't want that to happen but seems like some users are being dishonest with me.