.- You will have to come out of pocket for the arears, fees etc, just to get into "contract" some times $20k or more and all you have as protection is the word of someone who's proven to be unreliable and a signed piece of paper... 

Because now, legally, they have to disclose that if this all falls out.

If they have an legally binding agreement, you need to honor that agreement and pay the fee.If you failed to mention to the agent that they are going to get paid, and then explained how, of course they won't present the offer.

So, many landlords legally "bribe" these S8 tenants to move into these Neighborhoods/Properties with free appliances, TVs and internet.

.- Also, you need a legal way to take back the deed if buyer defaults!

The Rise of Co-Living: As Airbnb Faces Restrictions, New Housing Models Win in Court 🏡⚖️Across the country, cities are tightening regulations on Airbnb and short-term rentals, making it harder for property owners to operate legally.

So you want to check that out.I also ask how familiar are you with Spanish, and reading Spanish contracts, and knowing landlord/tenant laws in Spain? 

What if the person staying at your place signed a contract but their 1st payment check bounced.

One question that you may not want to post here for legal reasons, is how much are you paying your PMC?

It is an expense, but they keep it all legal and compliant.