Why Is Facing Not Reverse?

This sign make me stop by there and think for few minutes there when I looking for a car park at the Empire Hotel. I don't get it why they want the car owner park their car facing to the wall!!! As far as I know for safety reason and more easy to park nicely, normally is advise park reversing one. Even at Shell or MinDef you also see the sign say reverse parking one! But why here tell you to park Facing Wall... I do have a bit blur blur when I read this!!! Then after I took this photo and think in my car the only solution I can think is.... The Wall is dirty if we park the car reverse!!! That's the answer I can have!
Coz if we park our car Gostan way... when every time we start up engine the exhaust smoke or minyak blow out and kana the wall and make it dirty! So to prevent this they want us to park facing wall!!! 
Do you think that I'm right?