To be fair, some cars are just crap at clearing their windows of mist, especially at idle on the drive. I've just had the leaky air condensor replaced on my car (Nissan Note about 7 years old) and it's still shoot at demisting.
But yes if the demister doesn't work then there's no excuse for scraping the outside and using a cloth on the inside.
But yes if the demister doesn't work then there's no excuse for scraping the outside and using a cloth on the inside.