I have rented a room from someone who listed it on CL. He posted several photos of the room, interior, exterior, listed all amenities. When I contacted him, he replied with a photo of himself, what he does for a living, schedule, house rules, hobbies, etc. A lot of listings in that area were specific, such as female-only, male-only, pet-friendly, etc.
I have listed my condo rentals on CL with photos and a clear, concise description. If the caller didn't read it properly, can't speak clearly, is asking for a deal, etc. etc., those are red flags.