While many potential renters just assume that a landlord is legitimate if he appears to be, current events still warn the tenant to be wary. For example, in 2009, Newsday cited the case of a man charged for leasing out an abandoned home, amassing around $10,000 from a tenant who assumed he was legitimate over a span of months. While a situation such as that is unfortunate, it's also preventable. By taking a few precautionary measures, you can rent with confidence and discover a prospective landlord's legitimacy or lack of legitimacy.
Ask your landlord if you could see a copy of his deed to the property. This will show you without a shadow of a doubt that he is indeed the rightful owner.
Verify that the landlord has shown you an unforged deed to the property by going to your local courthouse or records bureau and looking up the county tax records for the property. This will tell you if he is indeed the one being taxed for this property.
Make a copy of the lease and take it to a lawyer before signing it. A lawyer can spot any fishy clauses or red flags immediately that might not be apparent to you.
Ask the landlord for previous tenants that you can speak to. In a large apartment building owned by the landlord, you can usually just hang around outside and approach people politely, explaining that you're interested in leasing and how they feel about the landlord. For renting single family houses, ask the landlord for some former tenants that you can contact as references.