We've lived in our neighborhood for 9 years and the neighbor's still barks nonstop at us, falling leaves, cars going by, lawn mowers, kids at the bus stop, people walking by, the dogs owners, their kids, other dogs, squirrels, rabbits...
It never stops barking even if it is taken inside; we love when they take him in and count our blessings that he isn't an outdoor dog.
I'd think long and hard before purchasing a home with 3 aggressive dogs next door.
I'd also be concerned that the owner didn't quiet them when he came outside.