I've been fooled into thinking a colony was dead in the past. Had to leave town in early Spring and because of extended travel didn't get back home until the weather had warmed and pollen was widely available. The assumed 'dead out' (silent despite rapping, hadn't touched the sugar left for them, no sign of cleansing flights) was now alive and kicking (the size of a baseball!!), thrived during the summer, made lots of honey and survived the following winter so I could make splits from it.
For this reason, I think it pays to wait a bit before deciding to clean out an 'assumed' dead out hive. Even a small cluster can survive if provided the chance and pollen is soon to be available. Ever since the above experience I now wait until the willows bloom before opening up or disturbing too much, an assumed dead out……..and I've been surprised several times discovering a small cluster of bees, some brood and the queen inside a hive I 'thought' was dead.
I can only hope that this Spring brings me such a surprise :-\ Only two months to go……. ;)