I have had just one foray into the 'buy-to-let' arena, and found a local housing association were offering reasonable guaranteed rental on fixed-term contracts - 2, 3, or 5 years. The rent they offered was maybe 7-9% lower than the market rate for the property - but it would be guaranteed for every month for the whole of the contract, no agent to pay, no empty periods, no worries about tenants defaulting, leaving, etc. They wanted it completely unfurnished, just carpets and curtains. I had to have landlord's insurance, of course, and also a gas service contract etc. Other than that I had no costs (only any repairs to the central heating, that kind of thing - but if I wanted the association would organise any work and just deduct the cost from my next rental payment), and the association were bound to return it in as original condition allowing for wear-and-tear. I knew it would be DSS tenants, and that it was likely to be short-term and emergency housing, so could be families with problems, and could be a lot of changes of tenant in the period. But I felt that the hands-off guaranteed income plus the nice warm feeling that I was providing a home for someone who was in need more than compensated for the downsides.
At the end of the period the association repainted throughout and replaced curtains; the carpets were still ok. (They hadn't been new.) I don't think the house was worth any less at the end of the period than it would have been on any other kind of rental.
I know this arrangement would often not suit any individual at a point in time where they are needing to rent a property out - but I did think it was a super arrangement if you knew you wanted tenants for 2 years or more and didn't need to be leaving the house furnished. Oh, and because the income was guaranteed, the bank were happy to take it as security for a mortgage on the property too.
It's rare, and very nice, when it's an everybody wins situation! (And I never had any complaints or worries from the neighbours, either.)