@Clau2 Nope, don't accept the reservation if they are unable to pay. If they can't make the reservation payment through Airbnb there's nothing you can do or should do for them. Don't let anyone talk you into any arrangement other than normal Airbnb procedures. They are there to protect you.
Right, lack of reviews should tell you something.
I wouldn't hesitate to decline and stop communicating with them.
I know that sounds harsh, but there are a lot of people out there that want to sweet talk hosts into doing something that's not in their best interests to do.
Remember, hosting on Airbnb is a business, pure and simple. It's not your responsibility to fix things for guests.