I’ve hosted 6 couchsurfers since I join this great community. They come from Taiwan, Hong kong, Malaysia and America. I didn’t thought it would be unsafe, probably because I’m also an out-going person like most couchsurfers. Actually if you worry about safety problem you may go to his/her profile and check references to help you make decision.
Every time I spent time with couchsurfers, we usually go and have a tour around the city, have a drink together, talk about culture difference, and share each other’s interests. It’s a great way to make friends, have a different view about this world, and also have a lot of fun.