Can A Male-to-female Transvestite Ever Really Pass As A Generic Female?

I assume you mean, someone who just dresses as a woman without surgery? (otherwise s/he would be a transsexual.) Well, in that case it would presumably be impossible to pass as a woman once one was undressed... but if you mean, while walking down the street, in casual conversation etc, then this has happened many times; and even closer contact, short of actual sex, has been managed.

Of course, it would work better if the man was quite feminine looking to start with (the example of 2003 reality TV show "Something About Miriam", where a group of men competed for the favour of a woman who turned out to be a man, is perhaps an extreme one since Miriam is a "transwoman", a biological male who has never really seemed or felt male at all.) But it should be noted that when the very macho actors Tony Curtis and Jack Lemmon were preparing for their drag act in "Some LIke It Hot," they tried it out on some passing women, not one of whom suspected them.