Most likely it is because when it pulled from the MLS's it did not have a photo at the time they listed it. So, that's how it went it Trulia. I don't believe Trulia goes back to pull newer pics or info. The agent must enter new info or pics manually on Trulia after the initial listing. I hear and see that problem alot.
Also, be sure that if/when you reduce your price that your agent comes here to enter it manually otherwise I don't believe it will update to the new price. I specialize in the 30115 area and see that all the time especially in that zip code.