1. Heat a large cast-iron skillet over medium-high heat. Add oil to pan; swirl to coat. Sprinkle both sides of scallops evenly with 1/4 teaspoon salt, sugar, and pepper. Add scallops to pan; cook 3 minutes or until done, turning after 2 minutes. Remove from pan; keep warm.
2. Cook bacon in a large nonstick skillet over medium heat until crisp. Remove bacon from pan; crumble. Discard all but 2 teaspoons drippings. Add shallots and garlic to drippings in pan; sauté 2 minutes. Add broth to pan; bring to a boil. Add remaining 1/8 teaspoon salt and watercress to pan; cook 30 seconds or until greens begin to wilt. Place 4 scallops and about 1 cup watercress on each of 4 plates. Sprinkle servings evenly with bacon.