Cut kernels from 6 ears of corn. Break remaining 2 ears in half and grate over plate on large holes of box grater. Combine cut kernels, grated corn, and any accumulated corn milk in bowl; set aside.
Cook bacon in Dutch oven over medium heat until crisp, 6 to 8 minutes. Using slotted spoon, transfer bacon to bowl with corn.
Add oil to rendered bacon fat in pot and return to medium heat. Add andouille and cook until lightly browned, about 2 minutes.
Add bell pepper, onion, celery, and ½ teaspoon salt and cook, stirring occasionally, until vegetables begin to soften and brown, 8 to 10 minutes.
Stir in garlic, tomato paste, and cayenne and cook until fragrant, about 30 seconds.
Stir in corn-bacon mixture, water, and tomatoes and bring to boil, scraping up any browned bits.
Reduce heat to low and simmer, stirring often, until liquid has reduced by three-fourths, 25 to 30 minutes.
Stir in reserved tomato juice and cook until liquid is reduced by two-thirds and mixture is slightly thickened and creamy, about 10 minutes longer.
Off heat, stir in scallions and season with salt and pepper to taste. Serve.
