Yes GH, I have witnessed K wing on queen-less hive. My experience is that few bees K wing as a result of being queenless so it is not a for sure sign. I have noticed a high percentage of queenless hives are loud and the bees exhibit nervousness. To the countary, I currently have a queenless hive that is both calm and quiet. Just today, I added a virgin queen to this queenless hive, the bees were so calm, as if all is well.
I?m a little suspicious of this queenless hive as the bees were too calm. So in a few days I will check for queen cells before releasing the virgin queen. I will also pay close attention to signs of queen acceptance or rejection.
Just a note, K wing can also be a sign of disease.
Blessings