Smurfjet - In relation to dangers highlighted above -
After washing an AeroPeru 757, workers did not remove adhesive tape that obstructed static ports. Occurred in 1996 near Lima, Peru. 70 people perished in that accident.
Not washing per se but improper or lack of procedures wrt ports, Birgenair 757 of Puerto Plata in Dominican Republic (c 1996) stalled due to incorrect airspeed warnings - subsequently causing the crew to ignore stall warnings. The probable cause of obstruction was surmised to be mud/debris from small insect(s) introduced to the pitot tube during the 20 days that the a/c was on the ground. The pitot-static system was not verified prior to re-introduction to service.