Although it may fit within the category of Respectful, I would add Aware. I had someone bump into the bar when I was benching, another who was so close to the squat rack that I almost hit him in the head with the bar as I unracked it, and a couple of people were swinging kettlebells so close to where I was squatting that I was concerned about contact. If I have to rerack the bar to have a discussion about personal space when lifting, I am probably not going to be in a good mood.
Don't remove plates from a loaded barbell unless you know that nobody is using it. Also, never take a plate off one side of the bar. I have left my stuff next to the bench and gone to find a couple of plates or get a drink of water only to find one side of the bar weighing more than the other.
During a holiday weekend when I was in college, there were only two of us in the gym. My spotter was a college wrestler that I had never lifted with before. After the bar came down to my chest, my spotter who was there when I started the lift was gone. Although there were at least 3 plates on the bar, he assumed that I wouldn't need help and went to the bathroom. Fortunately, I wasn't using collars because the weight was too heavy for me to use the roll of shame. The noise from the plates coming off on one side and the bar flipping was loud enough to attract the attention of people who weren't even on the same floor of the building.