What I learned after being there for 3+ years is that it was just like living in an Apartment as no-one knew each other and there were always people coming and going, lots of Parties and such and with the animals, a lot of the renters did not care if their animal urinated outside on the sidewalk, as they stated the dog had to pee.

I had a dog and cat while I lived there but they did not soil the floor - however we did think that perhaps it may have had something to do with the smell.

Seeing as many properties as possible will allow you to tell the dogs from the deals.Look into the first time homebuyer program through Mass Housing.  

Say Pets are allowed in the listing, let them open up about the 3 dogs and 4 cats they have, that way you have that information.

Sounds like he wants to owner finance to take capital gains in small chunks versus 1031 into other properties and that is why the owner finance.Owner finance can be good but not if you are overpaying.On face value it looks like he is trying to ( dump the dog property on you with the fleas first ).

I find that if you get an agent who really wants to make some money they will be a great bird dog for you. 

I don't have the answers to this question but I can tell you that I just replaced two bedrooms of carpet yesterday on a rental because of the dog.

In driving by one of the units I noticed a woman sitting on the front steps smoking with two small dogs on a leash. 

This is becoming worrisome considering we have kids and dogs in the home and it’s a fire risk.

Yes, it’s all roaming gangs and rabid dogs meander the streets.