to listen to the people downstairs’s domestic dispute, if they’re conducting it so loudly it comes up through my floor?
No more than overhearing a conversation while walking down the sidewalk, or while someone is standing in line and chatting on a cellphone.
I don’t think so, if you can’t help but overhear it. Now, opening a window or door to hear it better, that would probably count. And I think “polite” neighbors will try to turn on the TV or some music to avoid being privy to details of their neighbors’ relationship that their neighbors would rather them not know. But then I’m not a very polite neighor. 
It does seem to have levelled off a bit since the cold weather started. They used to hold them in the kitchen with the doors and windows open; now they tend to drift back and forth along the length of the house, although part of this morning’s interlude was conducted in the back yard despite the snow.
So, what are they usually arguing about and who do you side with?
Marital discord, apparently. Previous topics of controversy have included her weight, their IKEA purchases, whether or not he loves the dog more than her, and whether or not he should have married “some anorexic witch from Westmount” instead.
It’s hard to pick sides, because I can generally only hear her side of the argument (her higher voice carries better, and I think she yells louder).