In order to determine whether the character of Blanche Dubois is rendered as a parody of the Southern Belle, the first thing to analyze is whether Tennessee Williams intended to use her character traits to serve this purpose.
A "parody", is used specifically to ridicule something and to cause a comedic effect. It is true that, in the literal sense, the character of Blanche does over-use her Southern Belle traits to desperately block her dark secrets. However, Williams does not use these behaviors to cause mirth, but to draw out the pathos of Blanche's tragic flaws as a character.
If Blanche were to be a parody, the reader would find her actions funny. Contrastingly, all of Blanche's actions instill a sense of loss and nostalgia, as well as of pity and even commiseration. This is because Blanche is not really mocking her Southern Belle roots, nor is she laughing at herself for retaining the behaviors that she once used to exploit her good looks among the boys.
The tragedy is that Blanche is unable to move away from the same manipulative behaviors that would have helped her back in the day, when she was young and vibrant, and money was not an issue. She was, indeed, a glamorous and boy-crazy girl who had any man that she wanted and never lacked friends.
As the series of unfortunate events that lead her to lose herself completely continued to unravel, Blanche stuck staunchly to what she knew to do best: to create an appearance of over-the top personality, and to manipulate the men around her. The problem is that she did not know how to control this once-powerful skill and now it is falling on deaf ears. No longer can she show her charm around millionaire and powerful friends; she is now in the closest thing to a ghetto, living in an apartment with a rude and ape-like man and her abused sister. Blanche is very far from where she came from. This is not a parody, but an antithesis.
Even when Stanley tries to make a parody out of Stella it is hard for the reader to connect nor agree with Stanley. He comes out too strong and rude for any of this comedy to make any sense to the reader
Take a look at yourself here in a worn-out Mardi Gras outfit, rented for 50 cents from some rag-picker. And with a crazy crown on. Now what kind of a queen do you think you are? ...you sprinkle the place with powder and you spray perfume...and, lo and behold, ...you are the Queen of the Nile, sitting on your throne, swilling down my liquor...Ha ha! Do you hear me? Ha ha ha!
This would have been a humorous moment had Blanche's character been made to be a parody of a Southern Belle. However, the fact that Blanche is NOT a parody is what takes away the humor from the quote. Therefore, this supports the argument that what Blanche actually is, as a character, is an antithesis of what she once was, but not a parody.