I look at the entire add not just the pictures. The more detailed the add, quality pictures, the better the add is written is my first indication of who I want to deal with.
If a guy is to lazy to write a good add he's not serious about selling anyway.
Short adds, no pictures, poor descriptions or "listed for a friend" are all bad signs to me.
IMO no pictures or no no emails means they don't want to put things in writing. They would rather try to weasel out of a bad deal if they need to.