I agree with some of the other comments on specifying a max weight on dog size, bc Labs are really considered a mid size breed. I've found that being extra detailed on your rules goes a long way in avoiding misunderstandings. Putting them before the part with the wifi password is a great way to ensure that they're seen.
As for the argument. It sucks, it's not good for business with respect to neighbors, most of whom don't like living near hosts already, and if you're living in the same unit or on the same property, it's certainly not pleasant for you.
That said- no one goes on vacation to fight. We don't always know the circumstances that guests rent under, either- when my Dad was getting a kidney donation out of state, my family rented a place for almost 3 months, and it was often an emotional and terrifying time. More than once, we disagreed on the course of treatment, who was on what shift at the hospital, and sometimes over really dumb stuff, just bc everyone was stressed.
Obviously you hope that doesn't happen. If it was frightening, or you suspected damage, violence, or spousal abuse, you should call the police and let them help you sort it out (a police report also protects you as a host). If it happens more than once, you should definitely have a heart to heart with your guests about the expectations of the rental, and why. Sometimes people are loud without realizing it. Sometimes they're so caught up in the moment, common courtesy and the potential for disrupting you and your neighbors goes out the window. Mediating helps everyone get back on track. But if that was the only argument and only issue, I think having a modicum of compassion is part of being a decent human being, and an understanding host. You said it was a couple- odds are that at least one or both were embarrassed after the argument was over, and realized that you probably overheard. Maybe they were too embarrassed to apologize. Not their finest moment, but probably not indicative of who they are most of the time.
I don't think that there's anything wrong with you opting not to rent to them again in the future, it's your perogative as a host, and just business savvy (again, you don't want to risk upsetting your neighbors). I don't think mentioning the row in your review would have had any useful impact. Cussing is secondary to a lot of people and cultures, and anathema to others. I'd let that part go. For every potential guest, you have a 50/50 shot of alienating them over something as petty as verbiage. It sounds like you stated your issues with the dog, and that's fair, but again, I would be more specific in the future. Dogs are also like language- diverse, and what seems like a medium sized dog to one guest, might be entirely different to another.
