There are a number of rental scams going on in the Long Beach, CA area. The first kind and most promonent involve new listings for sale. Basically someone sees the property for sale and they take the data and pictures and enter them on rental sites as rentals. When you call them, they ask for a deposit before showing the property. They will say they are out of town or have a lot of interest and they want a deposit and then they'll send you the keys. They do this via wire so you can't trace them. Never give a deposit until you've met the person at the property and they have the keys to get in. Also, most of these have rediculous rents to make them attractive. If it looks to good to be true, its good to be true.
The other scam, which you may have been victim to, is when a family is in the foreclosure process, they may move out before foreclosure is complete (this can be many months) and then they advertise the home for rent to generate some income until the bank's real estate agent shows up to the property only to discover the previous owner rented it out. The best way to avoid these situations, is to contact a real esate agent, to run the addtess through their title company to ensure that the home is not in the foreclosure process.