Merlin
I've been back and forward to this one during its development - IMO its very good, clever word play and word choice.
I agree fluttered is not quite right. My only thought other than flickered, which works for the lantern but maybe not for Aphrodite is whether flirted might work?
One other idea - The shape of the poem could jar with a reader and I wonder if you reshape like below
Lost in a stark city
he chanced upon
Gropecunt Lane.
A red lantern fluttered
and swayed
like he imagined
Aphrodite would.
He unfolded his appetites
and walked towards
the ruby glow.
Clambered seven broken
stone steps,sauntered in
and paid the price.
do you create some feminine curves and also the final line of each stanza is a strong one.
Just a thought - maybe a daft one.
Elphin