I haven't had any that I have grown myself rot either, Tim. Whew! Rot really isn't an issue here, the winds are bone dry (5 to 10% daytime humidity is our norm) and and dry up any excess moisture before it can set in and fester. Different situation with these two though, very humid garden center and droopy rosettes that blocked air circulation. And not a single offset on either one sadly!
For jovibarba I am not sure how heuffelii cultivars would fare either but I have had several roller jovibarbas sunburn before where the parent plant was reduced literally to hay but the offsets survived and carried on. Not the same as rot
but a similar situation with a dying parent plant whose offspring survive the damage that did the parent in.
Marilyn, I'm not sure if mine would behave differently in my climate than in yours but for me, when mine go dormant in summer (not all of them do) the colors either become much less vibrant or they fade to just plain green (not a bad thing, right now one of my Rose Queens is a beautiful solid sea-green. My favorite color!
). Some of them will also droop and just look tired. I've never seen one of mine have wrinkly black tips when dormant. Some of them do get leaves with a slightly wrinkled/puckered look but they don't turn black or get soft.