Last game i played, someone played Disowned on me. I didn't have any money but I was sure I could just exhaust one of my slave to get the missing gold and counter the scheme but we couldn't agree on the feasibility of this move.
Is the action of exhausting instant or not? Do actions have priorities? We couldn't find it in the rulebook.
Jimmy is correct in his interpretation.
Any of your slaves / gladiators that have "exhaust to gain x" abilities must be used on your turn, much like house abilities.
the reaction card when it's played you must resolve it, so you cannot go to a different card to gain back the resource you're missing, while the reaction waits... if that were the case, i'd just wait till the auction phase is done so i can buy a gladiator, then resolve "A Shameful Ludus"
so to sum up: if you have no coins and someone plays destitute on you you lose a point. Then, if it's currently your turn, you can use your slaves / gladiators to attempt to gain some money.