Octopuses can't hear (except for tapping on the glass, or deep vibrations), so the vacuum cleaner or yelling won't bother them.
They tend to ink when startled, when they're "spooked" by something they didn't expect. An example - my bimac last year, Ollie, was asleep on the glass when I came to her tank first thing in the morning. I thought she was awake, so I turned on her light. She "jumped", inked, and went zooming off. I believe she inked 4 times in the 10 months I had her.
Nancy