Most French adjectives must be placed after the noun they modify, except for the BAGS exceptions (learn more). There are also a number of French adjectives which have different meanings depending on where they are placed. Generally speaking, when the adjective precedes the noun, it has a figurative or subjective meaning, whereas the adjective which follows the noun has a literal or objective meaning.

Here are the most common "fickle" French adjectives; if you know of others which should be added to this list, please let me know.

ancien
Figurative or subjective meaning
   mon ancienne école - my old (former) school
   un ancien château - an old château (now a hotel)
Literal or objective meaning
   mon école ancienne - my old (aged) school
   un château ancien - an ancient château

bon
Figurative or subjective meaning
   une bonne réputation - a good reputation
Literal or objective meaning
   un homme bon - a good (charitable) man

brave
Figurative or subjective meaning
   un brave homme - a good (decent) man
Literal or objective meaning
   un homme brave - a brave man

certain
Figurative or subjective meaning
   un certain regard - a certain (type of) look
   un certain âge - old age (euphemism)
Literal or objective meaning
   une victoire certaine - a certain (assured) victory
   un âge certain - old age (rude)
Word play: Certain âge et âge certain

cher
Figurative or subjective meaning
   un cher ami - a dear friend
Literal or objective meaning
   un pull cher - an expensive sweater

chic
Figurative or subjective meaning
   une chic fille - a nice, decent girl
Literal or objective meaning
   une fille chic - a classy girl

curieux
Figurative or subjective meaning
   un curieux homme - a curious (strange) man
Literal or objective meaning
   un homme curieux - a curious (nosy) man

dernier
Figurative or subjective meaning
   la dernière semaine - the last week (of the year)
Literal or objective meaning
   la semaine dernière - last week (the one before this one)

différent
Figurative or subjective meaning
   différentes idées - various ideas
Literal or objective meaning
   une idée différente - different idea

divers
Figurative or subjective meaning
   divers étudiants - various, several students
Literal or objective meaning
   des étudiants divers - varied, diverse students

doux
Figurative or subjective meaning
   une douce musique* - sweet music
   un doux parfum* - sweet perfume
Literal or objective meaning
   la moutarde douce - sweet mustard    la peau douce - soft skin

drôle
Figurative or subjective meaning
   un drôle d'idée - strange idea
Literal or objective meaning
   une histoire drôle - funny story

faible
Figurative or subjective meaning
   une faible chance - weak, poor, slight chance
Literal or objective meaning
   un homme faible - a weak man

fameux
Figurative or subjective meaning
   un fameux problème - a heck of a problem
Literal or objective meaning
   un vin fameux - first-rate wine

franc
Figurative or subjective meaning
   un franc imbécile - total idiot
Literal or objective meaning
   une différence franche - clear difference

grand
Figurative or subjective meaning
   un grand homme - a great man
Literal or objective meaning
   un homme grand - a tall man

gros
Figurative or subjective meaning
   un gros problème - big problem
Literal or objective meaning
   un homme gros - fat man

honnête
Figurative or subjective meaning
   un honnête homme** - a gentleman
Literal or objective meaning
   un homme honnête - an honest man

jeune
Figurative or subjective meaning
   une jeune femme - a young woman
Literal or objective meaning
   une femme jeune - youthful woman

*For this meaning, the adjective can precede or follow the noun

**Somewhat archaic

Quiz on fickle French adjectives