1- Because you choose
First of all, you have to keep in mind that by signing up for Couchsurfing you are not obliged to host anyone. Personally, I never host people with the uncovered profile ... Yes, I confess that I usually opt for girls who, like me, travel alone or for the poor pilgrims on the Camino de Santiago who, sometimes, run out of place in the shelters.
2- For its detailed system
Couchsurfers have to cover a form indicating all kinds of details: (time of arrival, departure, means of transport, why are you the chosen one ...). Contact them, exchange phones if you have questions.
3- Because the addresses are verified
All Couchsurfers who make a donation to the page are sent a postcard to their address with a code that they must enter on the Internet from their account: in this way, address is verified.