Why did Jim and Trelawney initially trust Long John Silver?

Jim and Trelwaney knew little about Long John Silver when he was intially hired for the voyage. To them, he was a former seaman, who wanted to join the crew as a cook. Silver's tavern was clean and well kept, and Silver said he would be able to provide the crew as well as the cooking. Both Trelwaney and Jim were inexperienced...... they would have been easy to fool, especially after the Squire allowed word to get out that they were going on a treasure hunt.