Place potatoes in cold water in a medium saucepan. Bring to a boil and turn down the heat to medium, letting them cook until fork tender, about 15 minutes. In a skillet, saute bacon on low heat until crispy. Place bacon on a paper towel and discard the grease. Drain the potatoes, but DO NOT rinse them under cold water. Rather let them cool for about 6 to 8 minutes on a sheet pan. In a small bowl combine vinegar, mayonnaise, mustard, scallions, onion, sugar, and salt and pepper. Transfer potatoes to a mixing bowl and sprinkle bacon and hard boiled eggs over them. Then fold mayonnaise mixture into the potatoes and serve at room temperature.