I'm writing this in English because I think the problem is that Lily still doesn't quite understand what DP was trying to say in Spanish -- and neither do I :( 

Oye DP, how about writing your sentence in English?

saludos

I had wanted to say "Perhaps, we were always drunk when we heard the Romans using the word and we might have misunderstood.

I can see that I could have legitimately used "usando" and that hayamos perhaps should have been hubieramos  and that I needed a personal a for los romanos and possibly a lo for the malinterpretado but Im saddened that its so confusing, certainly it aint funny no more.

Perhaps, we were always drunk when we heard the Romans using the word and we might have misunderstood.

I understand it to mean -- in English!!--

Maybe so; it's just that (or for that reason)....

And that is, in fact, how Lily translated it:

Quizás, es por eso que siempre estábamos borrachos cuando oíamos a los romanos usar la palabra y habíamos malinterpretado.

Steady now, hold on to your punctuation marks.  Let's remove the (oh joy) postpositive comma:

Perhaps we were always drunk when we heard the Romans using the word and we might have misunderstood.

So what about the rule that says you need a subjunctive after quizás?  The way I remember it is -- not always.  A New Reference Grammar  (p. 251) confirms:

...when the event referred to is happening in the present or happened in the past, use of the subjunctive is optional. 

Ok.  So if you have not already run screaming from your computer in horror and disgust, let me say:

1.  A little comma is a dangerous thing.

2.  It's permissible and often more natural to use the indicative following "quizás" when you are talking about events in the past.

3.  So what if your sense of whimsy is a bit more sophisticated than your Spanish grammar?  You've been working on it a lot longer.  And we all get hopelessly tangled up in our grammar here when we get bold enough to try something more complex than "Great lesson, guys!"  Or at least I do.  :)

Quizas, siempre estuvieramos borrachos cuando oíamos los romanos usar la palabra y hayamos malinterpretado.

dp, I got the joke  (if only because I don't speak Spanish), and I did laugh.

En cuyo caso, creo que se usaría estabamos :-)

I believe that you are referring to is the perpetual nature of the drinking and not to an alternate future

estaríamos borachos si los romanos no hubieran bebido todo el vino

thankyou all for your help xxx

Una vez cuando estaba en el Distrito Federal con una amiga, tomamos un taxi... Me senté en el asiento trasero y ella adelante. (No recuerdo porque ella tenía que sentarse ahí). Estaba disfrutando de la vista por la ventana cuando la escuché gritar: "¿Estás tomando un Modelo?"  Y de verdad, el chofer tenía entre las piernas una botella abierta de Modelo, con una mano en ella y la otra en el volante. Sólo me reí... pues, parecía bajo control. Como decía Marco, tal vez trabaje mejor en estado de ebriedad. ;) 

Bolivia: choferes no quieren decreto contra ebriedad