Further to the "washing".
In the current short term covers there is a blanking cover for each of the rear structure vents. Depending on the conditions of where your aircraft may be parked the air will flow in one side and out the other. Not good near the beach!
When investigating the EMB failures if you look really close you can normally see the water tracks with a strong light.
ECD do not condone the use of a pressure washer in their Information Notice.
The forward lower vents have been removed in recent production aircraft and a single vent is now integrated into the lower forward inspection panel.