The problem was it never occurred to them to ask about dogs or noise and, apparently, no one thought to tell them about dogs or noise and, in fact, they didn't actually visit their new house but maybe once or twice so they didn't actually get a good feel for the place until after they plunked down their hard, earned cash.
Imagine their surprise, and chagrin, when the full doggie orchestra got together and started their daily performances. Needless to say, the couple was none too happy. Yes, the Broker should have told them something. Yes, the former owner should have said something. They didn't and the couple moved in and, well...that's how lawsuits get started.
Thing is, when I bought my house, I visited the neighborhood in question during the day, at night, on the weekends, and on holidays. I checked things out as much as I could because that's what people do (or should do) before plunking down cash for stuff. They do their "due diligence" before trouble starts. Get it? If the concept is still a bit fuzzy, head on over to your local county law library and take a look at California Real Property Sales Transactions (CEB) or American Jurisprudence: State and Federal, 2nd Ed. (West). Those'll get you going in the right direction.