I think the parasite problem is/was not that bad outside of tourist hotspots. In fact, one couple that hosted me in Eastern Russia is frustrated that there are not enough visitors anymore, probably both because of CouchSurfing's decline and the Ukraine crisis. I've hosted a dozen people or so in an obscure Asian city, and none of them were parasites either.

I think the key here is "outside of large business/cultural hubs". If you had hosted in NYC or Hamburg your story could be different altogether.

I live in a rented apartment so I can't legally host on Airbnb - but I'd love to simultaneously room-swap with people in other cities when I travel... (Eg swap my place in London with someone in Berlin for a week or two)

I don't think you can legally do that if you can't legally host in AirBnB. You may, but e.g. my lease (before I owned my apartment) specifically limited non-family[0] stays to no more than 1 week at a time, and no more than 4 weeks per year total. On one hand, it is non-trivially onerous. On the other hand, I really liked the apartment, and I understood the rationale.

[0] the "family" was very broadly defined - e.g it explicitly included unmarried S/O and their family, and implicitly close friends. but it wouldn't have included "someone I never met and who found me on couchsurfing.org".

I had seen a site that does this[1] but think they are more geared to bigger residences.

May have small setups too..

[1] http://lovehomeswap.com

http://www.horizonapp.co may be able to help :)

some group unlock codes: couchsurfing airbnbhosts