I was talking about The Big Sleep, and we noted that it's one of those movies that sort of seems to make sense right up until you're finished watching it, at which point you realize that there were a million things that went unexplained.
It's not just the famous story (mentioned in the Wikipedia article above) about how neither Howard Hawks nor Raymond Chandler knew who committed one of the murders; it's that the movie builds toward a big revelation -- who killed Sean Regan -- that never really comes, at least not in a satisfying way. The way the final scene is played, the murderer could have been one of two people, and I've gotten into arguments about who the killer was supposed to be. (The obscurity of the final scene may derive partly from Production Code requirements: murderers had to be punished, so it had to be said that Eddie Mars, the villain, was the murderer, even if we were left free to believe that he wasn't. A lot of the obscurity in the film comes from the convoluted ways in which the filmmakers have to imply drug dealing, or nymphomania, or a lot of other stuff, without actually saying the words.)
But the other thing that has always struck me about The Big Sleep, and which I haven't seen a lot of other people mention, is that the whole movie comes off as Hawks's excuse to feature as many beautiful women as possible; not until the James Bond movies would an action-adventure movie lean so heavily on eye candy. The first scene is primarily focused on how good Martha Vickers looks in shorts. (The original script called for Bacall to show off her legs in her first scene, too, but either it was changed or she didn't want to do the scene that way.) Then there's the famous bookstore scene with Dorothy Malone, where Hawks turned a bit part into a long -- and mostly pointless -- scene because, by his own admission, he thought Malone was hot and he wanted to give her more to do.
I've always thought the iconic scene of The Big Sleep is the one where Marlowe gets into a cab to do the follow-that-car scene, but his driver is a good-looking woman. Obviously women are an important part of the Raymond Chandler world, but Hawks overdoes it to an extent that we wouldn't see again until Frank Tashlin came along. I'm still not sure what possessed him to do the movie that way, though of course I am grateful for Vickers and Malone.