Kim Basinger thinks it is about 'facade'. I suppose her bit is about facade. Ho hum. Kevin Spacey thought it was about the economic and political growth of Los Angeles during the 1950's. Right Kevin. You look way hot in those clothes too.
Now, listen up fellas, this is a film about intelligence. Vincennes walks under a cinema sign twice that says 'the bad and the beautiful' and of course they are all bad and beautiful (apart from Dudley Smith, who is just bad). But more importantly than that, they are all intelligent, and that draws them together. And that's what I like best of all about this film: it's an exploration of what it's like to be intelligent. All the different ways it strengthens and weakens you, and hurts you. And how it makes you notice other intelligent people, and feel interested in them.
A lot of the important dialogue is about this. And about the temptation to use intelligence to live an easy life. All three heroes go through big crises about how to use their brains. And also I think they are attracted to each other because of it. In particular I think Exley is physically attracted to almost all the other characters, which is why he acts so uptight all the time.
Vincennes and Exley see Bud White having sex with Basinger. Vincennes says 'He's not so dumb after all'. Exley looks at them, and wants... what? I think he falls in love with White right then. She certainly thinks so: 'fucking me isn't fucking Bud White you know.' Later, Exley stops White from beating him to death by saying 'Think. Think'. He has realised by that time that White can think. And from then on they stop trying to kill each other, and start killing for each other.