6. The water in the lavatories is very dirty.
Whatever you do, do not drink the water in the lav. It is bad enough to “wash” your hands in it. We sanitize the water tank at selected maintenance intervals, however parasites build tolerances to these cleaners.
Check the outside of the aircraft when walking in. If the paint is crappy shape, the plane is in crappy shape. Skydrol (hydraulic fluid) is a nasty fluid and will dissolve everything. So if the paint is missing, it’s probably from a skydrol leak. No one wants a hydraulic leak at 35,000 ft in the air. As you can’t just pull over and top the reservoir off.