>Anyway a "free" trial that asks for your cc number is obviously not free. Better to stay away of those to be on the safe side.

A few years ago I signed up for a "free" Audible trial and later forgot about it. They rolled it over into a paid subscription somehow and charged me money despite never giving them my card details in the signup process. I believe what happened is it got linked to my Amazon account and charged the card connected to that.

They refunded me after I contacted them but I didn't get the entire amount back.