Legal Question in Real Estate Law in California

If a neighbor or any of their invited guests are preventing you from having undisturbed enjoyment you may have a lawsuit. The police should be called a number of time before a suit is brought. But, the fact that the neighbor has homeless people visiting would be irrelevant to the lawsuit and would not infringe on your rights due to the person's status. Also consider that the court will not consider relatively minor disturbances a nuisance as we all live in this society but would have to actually be a disturbance to the average person.

Call the police. Be persistent. Talk to other's in the neighborhood whether the similar has happened to them. The key is to get in on the record with the police.

Then, you might pursue a nuisance claim; however, they are hard to win if the disturbance to you is considered "minor".

I'm rather doubtful that the police would intervene. I've heard that in such situations they shrug and say, "It's a civil matter!" You could try, but unless some law is being violated, such as a nighttime noise limit statute (rather uncommon), I think the police will be of little to no assistance.

As to a lawsuit for private nuisance, what you describe more or less fits within the description of an actionable infringement of your rights, but a successful lawsuit will require careful and extensive collection of evidence, and would be expensive, the outcome uncertain, and would probably provoke the neighbor.