A December midnignt in Paris

[Leanne]

First up, I read this as free verse simply because your meter doesn't work and so the rhymes seem irrelevant.  I'd tend to suggest not trying so hard to rhyme if you're not going to bother with formal structure.  Your need to rhyme is where you lose your meaning and make the poem seem forced.

A DECEMBER MIDNIGHT IN PARIS. 

From giggly passages of ground breaking erections, -- either the Eiffel Tower et al or a really good night for the zombies in Pere Lachaise
Past transparent blue yet impermeable nightgowns, -- perhaps "impenetrable" rather than "impermeable". Transparent and impermeable, though not referring to precisely the same thing, do not sit well together (and "impenetrable" gives you extra consonance)
Come double decker routes heading two directions; -- these two lines seem a little clunky to me.  I'd suggest something like "double decker routes head in two directions: junctions nearby or some faraway towns"
To either nearby junctions or far away towns.

Gathered across in varied shapes and sizes
Are fuel powered rodents in perfect alignment, -- I quite like this image
Waiting and watching up until the sun rises,
Ready to pursue their master's next assignment.

Two blocks ahead, in her fading peach splendour,
The friendless monster bids you a hopeless goodnight. -- "monster" really doesn't seem the right word.  "Skeleton"?  But then you'd have to change "skeletal remains" in the next stanza, which wouldn't be a bad thing, because it's such a cliche
She puts to bed her perceived slender -- see, this is a really good example of bad rhyming destroying/obscuring meaning -- slender is just not a noun
And falls to rest, though standing upright.

Below the fleeting rareness of the purple night
Stands the skeletal remnants of a once blooming trade
Whose absence left a party pleading for light.
Below is not age, but deprivation in its darkest shade. -- this is a strong concept, contrasting the excitement of the surface with the ignored underprivileged 

By this hour, frost engulfs benches and rails,
And the faint glimmer of lamp posts guides no one,
For most lie in bed dreaming up tails, -- tales, unless they're fantasising about puppies
Except for one man, whose bird nest hair was far from done.

Glued on him were fragmented sheets of faded flannel  -- these lines remind me of "The Streets of London".  It's good if you can fix up the rhyme/meaning issue
And the occasional patch of harsh, malnourished skin.
As he approached, he arrested our flowing channel,
And kindly asked us, with a mined out sort of grin:

Could you spare us any change lads? 

At change the colour of his song had fiercely decayed.
Perhaps capital for him was a painfully distant trade.
It then became clear to me, I'm afraid,
That I again saw deprivation, it its darkest shade. -- this stanza contrasts very well with the first