The normal rule of thumb is to have a clean lien

If you buy a regular second hand home, you need to a lien search to make sure that no multiple lien holders behind this property. Even if you are very sure that there is no complexity, it's still a good practice to conduct a lien search. It's not very expensive. You can do a quick lien search called Abstract of title (I forgot the official terminology).

In your case, either the bank or the seller must pay the tax. You must make sure that is taken care of in the sales contract.

The best practice is to avoid short sales. Rather, focus on bank owned properties. REOs normally have no such issue because banks usually take care of the bad lien situation.