In a large skillet, cook the bacon over medium heat until crisp. Transfer to a paper towel-lined plate. Reserve 2 tablespoons bacon drippings and discard the rest.
Meanwhile, bring a pot of water to a boil on the stove. Cook the spaghetti according to package directions. Drain well.
Heat the reserved bacon drippings in the skillet over medium heat. Add the asparagus and cook, stirring occasionally, until crisp tender -- about 5-7 minutes. Season, as desired, with salt and pepper.
In a large mixing bowl, stir together the spaghetti, asparagus, tomatoes, roasted red peppers and parsley. Crumble the bacon and add to the bowl. Toss well to combine. If desired, season with additional salt and pepper.