Be sure to read your specific Purchase Agreement. There is NOT an industry standard. The ones I've read said Buyer can cancel and get deposit back for 10 days from the
Buyer's signature. That is what My current
DVC resale (in escrow) purchase agreement states. I would also be sure to read "how" to cancel since verbal may not protect you.
If the Seller "never" signs it, or signs after a date specified in that document you should be entitled to your deposit back but frankly, it's less stress to keep your money (whether a deposit or the final payment) than to fight to get it back if you have an issue

that's why a number of Buyers do not send their final payment until the Seller has returned all documents.