More French Grammar weirdness

In French, often the adjective comes after the noun, so you don't say "a white house", you say "a house white" - une maison blanche.

So far, no problem. But, there are some adjectives wich always come BEFORE the noun, like the adjective "old". So in Fench you say "an old house, white" - une veille maison blanche.

The adjectives that come before tend to concern notions of age, beauty, size or goodness (mnemonic BAGS)

All this is still OK because you can always memorise the exceptions.

Then I came across a doozy - the word "propre".

If "propre" comes AFTER the noun it means "clean" but if it comes BEFORE the noun it infers ownership. So "sa propre voiture" means "his own car" but "sa voiture propre" means "his clean car".

Stupid language