I would try to deal with the IRS directly. But your best bet so we're not all chasing our tails here since its the weekend is see if the county has info online that can be researched or not. If so it's not much different than title company will do in researching title. However, I'd be speculative. As most the time the IRS doesn't put liens on property unless they think there may be assets above and beyond the home.
What I'm implying is that the owner may have other people trying to put liens on his property that don't reflect in county records for whatever reason but may be shown by other contracts or credit bureau.
Therefore, what is it you are hoping to obtain? If there is IRS liens and a foreclosure is it a deeply discounted property that will allow you to make enough to substantiate taking care of the IRS liens, other possible liens, repairs, hold time? Have you looked at days on market for properties in this area? Unless it screams OPPORTUNITY you may want to run :)