All that has been mentioned already, and . . . I recently, temporarily adopted two colonies from a local beekeeper friend - so I could manipulate them and tame them down again.
One was a top bar hive with twelve top bars - The outside top bar was drone comb and filled with nectar/honey/pollen, one other top bar was entirely older open larva, all the others were capped worker brood. This top bar hive had just swarmed (so were temporarily queenless), and that, combined with a lul in the flow, just prior to the main flow, which is soon to begin, they had become temperamental, quickly sending out a dozen or so defenders, when approached or manipulated. Not full-blown AHB defensive, but more than their keeper, a relatively new beek, had experience with.
The other one was a Langstroth, in three 8-frame medium supers. All three supers were full of bees, combs, honey/nectar/pollen/brood. The bottom two supers; though they had mostly foundationless combs, the frames had been hand spaced, evenly from side to side inside their supers, and in a few of the frames, the combs were fastened on an outside edge of the frame Top Bars, instead of being centered on the Top Bar (as they should be). I will need to detach these, and refasten them appropriately in the centers of their top bars. The top super had been added as a box of empty foundationless frames - the bees had taken this as their opportunity to cross-comb the entire super. Like the top bar hive, this hive had also recently swarmed -- I was only able to confirm this, after I drove the bees from the cross-combed super, where there were plenty of swarm cells, a few of which had already emerged. The crossed-comb was primarily honey, which I left exposed and it has already been robbed clean - I'll harvest the beeswax, then reintroduce the frames between brood combs once the colony has finished being requeened with one of my cultured cells.
So, basically, both of the colonies I've described above, were being problems for their owner, due to convergence of several of the issues described earlier in this thread. There may also be a contingent of genetics involved, possibly AHB, where a small percentage are of those genetics are being over-defensive, and their numbers are greater, now that the population has expanded exponentially. My estimation is that, that percentage is small (if at all), since they exhibit no other obvious AHB-like traits.