I'm sure the airline people are not amused, having to constantly reassure their paying passengers that yes, their pilots CAN find the correct airport.
"This is your captain speaking. We will be landing at Sydney in four minutes. If you look out of the left side of the aircraft, you will see a sign painted on a rooftop saying "Welcome to Perth". That sign is not correct. If you are distressed by this, we suggest you call the owner of the building and tell him so. His business phone is, his home phone is, his cell phone is, and his wife's cell phone is . . . "
Bet he goes and buys a bucket of paint right quick . . .