Frowzy Windows

When I was in Taiwan last month, I went to the top of Taipei 101, the world's tallest building.  As my friend and I were walking around the observation deck, we spotted a sign that made us chuckle.  It said:

 "If you find the windows are frowzy, please allow us a time for preparation. And if you happened to meet the washers are working, don't forget to wave at them and take a photo for such an unusual occurrence." Frowzy??  

Another classic example of Chinglish, I thought. 

Not so fast!  When I got home, because I couldn't figure out what word I thought was being mangled, I began to wonder if frowzy was indeed an English word.  So I surfed on over to Dictionary.com, and discovered that, sure enough, frowzy is an English word.  It means 'dirty and untidy.'

Who knew I had to go to Taiwan to learn a new English word?!