Good advice below. Basically, be prepared to get rid of any fabric or cloth items in the home--carpets, drapes, window coverings, etc. Thorough washing and cleaning might work, but it often doesn't.
Dan's advice about encapsulating the odor is good. However, before you do that, thoroughly wash and clean all the hard surfaces. If you use Kilz--a very good product, by the way--use the original formula.
I've also had some success with ozone machines. You have to use a heavy-duty one--you can rent or buy them. Check with your Realtor--he or she may have a source. Then you have to blast the home. They work well on things like cooking odors and smoke. (They don't work as well on things like cat urine. I know; I've tried!) I bought one from this company: http://www.maxblasterusa.com/
There's also a lot of good information on their web site.
The main point is that you can't just cover the odor up. You have to remove anything that's capturing the odor. You have to clean and then encapsulate hard surfaces. And you have to get to areas (with an ozone machine) that either you overlooked or you couldn't reach.
Having said all that, if the house is a good one--meets all your requirements--and it's priced low enough to compensate for the time and effort you'll put into getting rid of the tars, the odor, etc.--certainly consider it.
Hope that helps.