I would say that the day he gives up and starts selling his properties just to get rid of them is probably when you can call “bottom”.
Nawww.. because some knife catcher is will try to pick them up.. (greater fool theory). It will be hard to tell who the last and greatest fool is.. because somewhere in there, some of the smart patient ones will be picking up the properties. I would look at debt income ratios and monthly payment burdens.