plus this is just a contract...so whenever you find the title unmarketable, you can cancel the contract and get your downpayment back.
contact your lawyer and make sure that it is been written into the contract that if anything renders the title unmarketable, you have the right to cancel the K + get your money back.
in most of the case, people won't order title search until they sign the K; so when you order the title search, you will know what is going on there.