1. All accomodations are available (w/d in unit, pets ok, wheelchair accessible, furnished!) - eliminating listings with all of these checked will nearly eliminate the scam listings.
2. The description doesn't include any information about who's the renter. Usually the landlord or property manager will mention something about themselves.
3. Professional photos. This in itself is not a giveaway, but given the above two clues, almost always indicates the photos were taken from another listing. A reverse image search can confirm.
4. The deal is too good to be true. Know the market. $4.5k may not be enough to get you a furnished luxury 3BR single family home in the Bay Area.
I've had to browse through a lot of CL listings in the Bay Area and these are the nearly guaranteed ways I've found to eliminate the scam listings.
If that's not enough, I start my emails with requesting times of showings. If someone isn't willing to commit to meeting and showing me the place, I won't go any further.