Cook bacon until crisp; drain on paper towels. Crumble 4 of the bacon slices. Reserve the remaining 4 bacon slices and 1 teaspoon to 1 tablespoon of the drippings; discard the remaining drippings.
In a bowl, combine mayonnaise, milk, honey, lemon juice, the crumbled bacon, and as much of the bacon drippings as you like. Season to taste with salt and pepper. Stir until well combined.
In a salad bowl, lightly toss spinach, mushrooms, tomato, and eggs. Pour the dressing over the spinach mixture; toss to coat. Garnish with slices of bacon. Makes 4 servings.