If I had the ability to appear and disappear I think I would use it to do some good. Could you imagine how badly you could scare people doing really bad things if right in the middle of a robbery or kidnapping I appeared , grabbed the victim and disappeared with them. Or if I knew some one was trapped in a mine ,a cave or a burning building I could get them out. I could also take air, food and water to trapped miners or earthquake victims to help until they could be dug out.
If I wanted to go to a concert or play and it was sold out I could just pop in and watch it. Then disapear when it was over and not have to worry about the crowds trying to leave. I could travel like that to. Anywhere in the world I wanted to go. I could leave after breakfast and be home for dinner. I would be able to go anywhere and still be in my own bed sleeping that night.
I could also pop into any closed meeting in the world and find out what was really taking place and be gone before anyone tried to stop me. Imagine the commotion that would cause. I would have a lot of fun doing that.