I define cruelty as causing unnecessary distress to something - and bees can can be distressed by things that I do as a beekeeper, some of which I feel is justified, such as checking for disease, since I have a duty to look after them. If, when I go to inspect, I feel they are not in a mood to accept my intrusion - I leave them alone.
As illustration, I put in crown board with porter escapes to clear them from a super - I happened to be near the hive about an hour after I had done this, and could hear the commotion of bees in distress - I suited up and lifted the lid, they were beating wings, and all had thier tails in the air exposing their Naserov glands. I couldn't leave things as they were, and removed the crown board and escapes - (we will design a hopfully better clearing system for next year) To leave it as it was, I would define as cruel.