This authoritative word from Belle Époque Paris on the matter of proper Tango gowns was published in this 1913 article and accompanied by seven illustrations.
"What shall you wear to the Tango Teas? Let me whisper to you a secret, only to be revealed when it is found out, my dear, there is no Tango in America, or, at least in New York. But it is quite different in Paris and it is for Paris and the Tango that the French dance frocks are made."