First almost never ever does a property with a mortage though a bank or loan company ever sell at the auctions, the bank pays the tax at the very last minute ( like the day before the sale) and adds it to the loan and then may start thier own foreclosures.
If they do sale at these sales, the tax sale is suppose to clear it.
BUT, what state, since the law differs 100 percent from state to state.
In most states you don't get a deed to the property the day of the sale, you get a tax certificate which you hold for 1 to 3 years which is the time they have to redeem. So you do need to find if there is a redemption period in your state. So after the redemption period you turn your cerficate in for a deed.
Each county in the US holds these sales at least once a year, they are normally held on the county court steps, and you have to have the cash or approved check the day of the sale.
If you live in a state where you get a deed the day of the sale, and there is someone on the property, you serve them with eviction paperwork and if they don't leave with proper notice, you take them to houseing court for a legal eviction.
The deed you get varies by name, I have not heard of it called a referee title, I have seen it as a tax deed, a sheriff deed or a special deed, but I guess this is what your state calls it.
If you want to be sure the title is clear, you will have to do a motion in court to prove the title clear.