The contract states that the seller is obligated to provide a clean title. But to ensure that you wouldn't be liable for any clouds on title after closing (it happens) make sure you buy an owners title policy. If you're borrowing the money to buy the home, your lender will require you to buy a lenders policy. This policy won't cover your interests. So you will also need to buy an owners policy. And when you buy the lenders policy, the cost of the owners policy is just a little bit more (not double).
If you're paying cash, make sure you buy an owners policy. This will guarantee that any title issues that arise after closing won't be YOUR problem.