Ask them to show you receipts, cancelled checks, money order receipts. Ask to see their lease or rental agreement.
But, unless they have a lease that you must honor, you don’t much care what they used to pay. You want them to pay whatever amount you determine is correct. You should know rents, or quickly find them, for other properties in the area.
If a judicial sale, where a lawsuit is filed, generally they will name John Doe, Tenant and Jane Doe, Tenant as Defendents to the suit… What this means is, they are put on notice, being a named party to the suit, and therefore any lease and Tenants ould be rights should be averted or eliminated as a result of the foreclosure action…
You can require new lease, or just go ahead and evict… any standing lease should be determined to be invalid…
But then good ole JT is a real estate investor, not an Atty.
I imagine that even though you bought the house at auction, if there was not a lease stipulation, you should be able to require a new lease or evict the tenants. If the tenants complain, tell them to take it up with the original lessor. Otherwise start the eviciton process and look for new tenanats on your terms.
If nothing else, the judge will answer your question one way or the other.