One idea I had - which I admit I haven't thought fully through.
What about film noir, and dashell hammett detective stories?

As I naively see it, Marlowe is a lot like a film noir detective, trying to solve a mission in circumstances that throw him around and often times out of his control, with lack of clarity and truth.

One of the reasons I mention Blade Runner, is that one of the versions has voice-over to explain Deckards internal thoughts (I'm aware a lot of people hate that.

The reason I think of usual suspects, is that it also has an enigmatic storyteller, who was personally involved in the story he reveals to us.

Personally I don't find Marlowe unlikable. He's sort of neutral - neither good nor bad, a bit like Eastwood's blue-eyes. He's swimming and surviving in a racist ocean, and for that, I don't see him as particularly racist, especially as he notices and highlights the pointless racism he is witness to. He doesn't condone the senseless beating of the random slave during the fire, and he also has contempt for the greedy morons brainlessly shooting their guns at the river bank foliage.

To me, he is more like a visitor to dante's inferno, and it appears to me he is repusled, but probably desentivized to the suffering and cruelty he witnesses.