Please note:
I have the greatest respect for our engineers, in fact I'm a qualified aircraft engineer myself!
I always take the time to clean and tidy the flight deck upon leaving, I encourage my colleagues to do the same and I certainly do not expect any engineer to clean-up after me.
I'm advocating and calling for airline managers to implement a periodic, perhaps hangar input, deep clean of our work place in the interests of hygiene and health. This deep clean should be considered a specialist function using specialist equipment with adequate man-hours allocated to task.
And for clarification, I spent some time upside-down in the seat trying to recover the aforementioned water bottle from behind the rudder pedals without success so in the end had to enter the problem the tech log.