You need to do a title search. All states and counties are different. I work in DuPage county, IL. The auction prices around here end up too inflated because everyone thinks if its an auction, its a deal, and they bid them up.
I go to the county building and search the title all the way back as far as I can. Add up all the leins to figure out how much to offer. Remember, if they haven't been making payments - what they owe can actually be more then the original mortgage.
Around here, you need a cashiers check made out to yourself for 10% of your maximum bid price. then, if you win, you have 24 hours to bring back a cashiers check for the rest. Then, you have to wait a week or so for a judge to "approve" it. If you get some bleeding heart, liberal wacko democrat judge, she may feel sorry for the 15 illegitimate kids living in the house and deny the sale. Then, your money is tied up for 2-4 months while you fight to get it back. If they approve the sale, then the people have 15 days to get out. You have to PAY to rent the sheriff to go to the house for $250. Then you show up with your own movers ($$$) and have 90 minutes to clear the house out and put everything on the lawn, no more then 150 feet from the building, and accessible to the owners. YOU have to protect it from thieves and rain for 48 hours. After 48 hours, you then have to remove the stuff that is left or get fined. If it takes you longer then 90 minutes to empty the house, then you have to rent the sheriff for $150/hour longer. You cannot empty the house, or be in it (until after the 48 hour thing) without a sheriff present. Now, after all this, and trust me, the people have trashed the house because thats the type of trash they are, you get it.
IMHO, if you want to make money, you HAVE to get the house before foreclosure and it goes to auction. You and thepeople have many more options. Good luck!