If I buy a first position loan at a Trustee's Sale, what else will I have to pay?

If I purchase property at foreclosure auction and the loan that I purchase is in first position. What other type of liens stay with the property that I will have to pay

You will always want to check for delinquent or current property taxes. If the loan you are purchasing was a refi you will also want to check for any family support judgements or any other liens or loans that are superior. If you see a prior loan was a home equity lien of credit always verify that a reconveyance was recorded. Additionally, if you are intending to flip the property you may also want to check for IRS liens since there is a 120 day redemption period on IRS liens.
If you look in the Forums you will find some great threads on which liens are wiped out at trustee sale.