No shit. Sometimes I wonder how all these LPT's make it to the front page. 90% of them are common sense or lessons your parents should have taught you. Even if you're on a first name basis with your boss and/or shoot the shit behind closed doors you can never assume that you're friends or that... that... relationship carries on in front of other staff or what you say will be kept in confidence.
Another LPT, well just a story really, and you can take it for what its worth. My first job after (dropping out of) college, I was basically a grease monkey/ scut runner type. I did have some defined duties and was expected to be at one station though. Well I happened into a storage area that the old employees had really screwed up, their haphazard bullshit caused me to spill a fucking pyramid of uncovered paint cans. So I go out, the owner happens to be sitting with my manager, I go out and tell them I basically just poured paint on every single fucking thing in that storage room. I'm going to work on getting it clean, I won't be at my station for a while. Didn't ask, didn't apologize but didn't try to throw anybody else under the bus either. The owner came up to me a couple days later in private and asked me why I took the fall for it. He'd seen what that area looked like and knew it was going to happen eventually. I told him "I didn't take the fall, I never said it was my fault. But I didn't think you were concerned about the who, how or why I just let you know the problem and that it was being fixed."
Anyway, thats how I got offered a salaried, degree required, management position 2 months after starting at the bottom. He offered to pay for me to finish my degree. I turned it down for personal reasons. Nobody clapped, his name wasn't Albert Einstein, its not an amazing story but its true.
What my point is, and the LPT is:
The whole "well so and so did this or that" cop-out has no place at work, leave that in gradeschool. When there's a problem, the boss doesn't care who caused it, the boss only cares that its going to be fixed. This is something my father taught me way before I started working.