Funny, I once had my master carpenter berate me for saying please and thank you to him after he did anything for me. He thought it was condescending, and implied that he was below me. His exact words to me were "There is no assistant after my title."
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I ran into this one time as well... Which is odd because I feel like it shows the opposite. If you work "under" me, I can just tell you what to do (not that that's my tactic but the implication...). If you are above our equal, I need to ask. People intrepret things differently all the time - not too much you can do about it. You can just do your best to dissolve the situation. For me, it was really hard not to respond "THANK YOU for bringing that to my attention. PLEASE accept my apology if I've offended you."
Back to word choice:
Using *I* instead of *you*. I can't think of a great example but ChaCha touched on it with "I feel..." I'll edit later if I come up with something brilliant.
Offering the problem and not the solution. ie. tell your house props that the actors are concerned that they are slipping on stage. Let the prop guys offer the solution. 1) less of an aire of telling them what to do 2) they may know the answer better... ie. adding more slip-no-more is actually detrimental; it has built up too much so he'll strip it down and add a fresh coat.
**NB: when I first wrote the above I wrote "the actors are complaining" and changed it to "are concerned". It's easy to dismiss a complainer, but how do you ignore a concern. *concern* also implies that I take it issue seriously versus *complain* which implies "just give me an answer I can tell them to get them off my back".