Now, I know what you're thinking, if Bette Davis had ever played this classic W. Somerset Maugham character, this would be a no brainer. Alas, Bette did her own version of a Maugham wanton woman in "Of Human Bondage"(1934). What is interesting about this comparison is that one giant aesthetic different. Gloria Swanson made "Sadie Thompson" in 1928 as a silent version, while Joan Crawford followed with "Rain" in 1932 with sound. 4 years seems hardly enough time between an original and a re-make, but the advent of sound made it imperative to give poor Sadie Thompson more of a seductive edge, incorporating verbal innuendo with suggestive gesture.
It's the age old argument, sound vs. silent.
This is one that is particularly interesting because it is from the same source material. If we look at both films from a strictly visual perspective, both are pretty much identical, both Swanson and Crawford don ridiculously comical hats, wear make-up that would make Divine jealous, and accent their face with an ever-present dangling cigarette, as if to suggest that they are women who do the wrong things. They are both suggestive in their gestures, not afraid to stroke an arm or push hair out of the face. They love to dance and drink, and enjoy life; their movement suggestive of a women who are definitely sexually aware, as I'm sure that pelvic thrusting was pushing it too far at the time, their movement suggest a disposition of a harebrained party girl with loose morals and a penchant for drinking.
Though this does not spell out in plain english that Sadie Thompson was a whore, it is enough to convince the main antagonist of the film, Mr. Davidson that she has a seedy past.
The irony of both of these portrayals, is that Sadie Thompson could easily fit the "hooker-with-the-heart-of-gold" label which that era of American cinema loved to exploit, Sadie is not aesthetically reformed. She may not be charging for sex anymore, but she doesn't shy away from a shot of Scotch or a suggestive dance with whoever is ready to party as to forget about the thunderstorm conditions of the tropical island of Pago Pago.
Sadie doesn't take every drunken sailor at the hotel into her bedroom, but instead falls in love with an oafish awkward boy who is definitely not up to her sexual par. And when Mr. Davidson tries to bring the law on her, articulating that she must be truly punished for what she did (i.e. it's not enough to stop being charging for it, she must dress and act like a nun, and to do so must go back to where she came from), she does not try to seduce him, which judging by the circumstance, would be her best bet.
So to answer this question, we cannot look at Sadie considering her motivation and disposition, we have to approach the character in both films as an icon. She is a symbol of rebellious womanhood, and can be perceived as a paragon of feminism. Rather than compromise herself, she chooses to stand up for the right to smoke, drink, and wear copious amounts of lipstick, and who does this better? Sound aside? I would have to check the box for Joan Crawford. Her performance is both intensely sexual and profoundly disparaging. Gloria, bless her heart, goes for the point by point recreation of the story of "the downfall of Sadie Thompson" without really breaching the essence of her womanhood. But judge for yourself, unfortunately both films are in horrible condition and very rare on DVD. Ridiculously enough no one has bothered to restore either. It seems even the likes of Crawford and Swanson can't resurect interest in W. Somerset Maugham, but it is one of those rare cases where the cinematic interpretations of the original source material is actually more telling. Who is the bigger slut? Definitely Crawford, and I say that in the best way possible. I think within the confines of Sadie Thompson, it is a form of dissent and rebellion, and a admiral way to appear. Amidst a veritable who's who of future church elders, the contrast of sexual openness and ambivalence is more prevalent in "Rain".