Thank you for your question about tax lien foreclosure properties.
If you are looking for a possible investment I recommend using RealtyTrac.
Please be advised that I rarely recommend using RealtyTrac, however, the information they provide is necessary to 'level the playing field' because professional investors have saturated the auction market.
Based on my education and experience it is very hard to 'get a good deal' at an auction because professional investors know what to bid and when to stop bidding.
RealtyTrac provides loan and lien information on prospective properties. Loan information helpful because you still have to clear the loans. Furthermore, there database can show you comprable properties in the area that have outstanding liens.
If you do decide to sign up for RealtyTrac please do not forget to cancel when your free trial ends or when you find a property because they will continue to charge your account.