All NOD and NTS as well as trustee’s deed are posted in the public records. Every REO goes through a process where it is sold at the courthouse steps. The homes you see getting bought before listed on the MLS are being bought at the courthouse steps.

Pay services like ForeclosureRadar and RealtyTrac track and aggregate the data for you. There are posting sites like fidelityasap and priority posting which publish NTS and opening bid data.

If the property wasn’t distressed before being purchased it was probably just investors door knocking or putting out bandit signs (“we buy ugly houses”) and buying the house cheap off the owner.