I wonder how this kind of thing plays out for people that don't have anywhere near $50k available. I'm assuming since the company worked first and then invoiced, that the options would be either (1) sell the house and use the proceeds (assuming equity exists) to pay off the cleaning, or (2) declare bankruptcy.

If the company were to require pre-payment for cleaning, then it's really just down to either (1) abandon and have the bank seize the house, or (2) sell the house for pennies on the dollar to an investor.

Things like this (well, not this exotic, but like a busted sewer line which could cost $20k to replace) used to keep me up at night after we "bought" a house. I've found I can rest by mentally reframing the mortgage as rent and knowing that an "out" (strategic default) is always there if something goes very expensively wrong.