Check with your local county office to find out how sales in your area are handled, but common threads among most of them are:
No loan contingency
Sealed bids
Proof of financial qualifications
Sizeable earnest money deposits
Purchase property "as is"
Sometimes buyers are not allowed to inspect the house before making an offer. The problem with buying a house sight unseen is you can't calculate how much it will cost to improve the structure or bring it up to habitable standards. Nor do you know if the occupant will retaliate and destroy the interior. On top of that, you may need to evict the tenant or owner from the premises after you receive title, and eviction processes can be costly.
Most have liens and clouds on the title that once purchased, you are responsible for taking care of.
Discuss Trustee Sales with Repo4Less before you attempt this tactic.