Let me just make it clear that there are only two avatars authorized to accept payment on behalf of Desperation Isle Estates: Wildefire Walcott and Illana Ireton (my alt). If anyone else attempts to collect rent from you and claims to work for me, they are lying, and you should file an Abuse Report against them immediately. (And also report the user to me, as well as the sim they tried to rent to you, so I can report them as well.)
With that out of the way, if you're looking for a homestead or full-prim sim from someone who WON'T scam you, just search in-world for this phrase: for rent desperation
You can tell a sim is ours by checking the Covenant tab of About Land. My name, Wildefire Walcott, will be listed as owner, and there's even a note in the covenant listing me and my business alt as the only authorized players to collect rent.