I also believe that you (and the others turned away who didn't come back in "proper dress") aren't their "target audience"; while you may well have enhanced the party, it was a surer bet for them that others would.

Nothing I'm saying contradicts that -- what I've been saying, and still hold to after all this discussion, and even now that I have a much better idea of what the party hosts intended -- is that, under that dynamic, the party shouldn't be advertised.