What is a dry mortgage?
"Dry Mortgage" is a slang term for Non-Recourse loan.

If you have a nonrecourse mortgage and can no longer make the payments, the lender can foreclosure on your home but cannot "bleed you dry" by garnishing your paycheck or seizing any other assists if the eventual foreclosure sale nets a price that's less than the outstanding balance of the home loan itself.

That's a lot different than a "recourse" loan, which permits a lender to tap your pay or even grab personal items to make up for the shortfall in sale proceeds.