As with many of these mass-attacks, even if 1% of the owners detects that their device (eg "smart"fridge) is participating and disconnects it, it does not really impact the continuous "wave" of attacks.
The problem is indeed that you may (not) be aware of these things to happen, if cpu is running at 100%, that fridge will still work. On the other hand, if it's on a NAS, you could "experience" a slowdown or even "lockdown" of your device. But cpu is not often the required factor, it's packet generation on a multi-scaled (worldwide) level, targetting a single spot. Many of these botnets are just "sleeping", as timing is of essence: if the bots awake too soon, the wave is uncoordinated, the lesser the impact.
So detecting that you are infested & participating in such a coordinated attack is a redundant question, because it is already (far) too late. The relevant question at stake is: how can you avoid being infested. And then the story of vlans come back in place: don't let your "internet devices" infect your "sleeping" and "never receiving an OS update" devices. Never ever let these "sleeping" devices contact the internet.
