I had some really good experiences on couchsurfing (hosting and surfing) about 10 years ago, then I moved to a very touristic part of the world, and started getting 90% of requests from couples who were basically looking to get free accommodation for their holidays. I accepted the first 3 times, and each time they would arrive in the evening, unpack, drive to a restaurant they had already booked, come back to sleep and then leave first thing in the morning.