Line a plate with paper towels and place the bacon in a large (cold) skillet. Turn the heat to medium-low. Slowly render the fat off of the bacon and when it’s slightly crisp, remove to the lined plate and cool.
Drain off (and reserve) all but one tablespoon of the bacon fat. Increase the heat to medium-high and add the scallops in a single layer. Sprinkle the tops with salt. Sear on one side for about 3 minutes, until the scallops develop a nice deep golden crust on the side in contact with the skillet. Remove to a plate and set aside.
Reduce heat to medium and add the shallot. Cook, stirring to coat in the oil for a minute. Add the wine and the vinegar, and deglaze the pan by stirring and scraping as the wine bubbles. When the liquid is reduced by half, add the beans and simmer until warmed through. Taste and add salt as needed. Add the spinach and cook, stirring, until fully wilted. Add half of the bacon and stir to combine with the beans. Simmer for 5 to 8 minutes. Taste and adjust seasoning.
Reduce heat to medium-low. Nestle the scallops, seared side up, into the spinach and bean mix and cook without stirring for 2 more minutes, until the scallops have warmed through. Top with a few twists of freshly ground black pepper and the remaining bacon. Serve hot.