For dressing, in a bowl, mix vinegar, sugars, juice, and Worcestershire.
In a medium skillet, warm brandy. Remove from heat; carefully ignite brandy. After flames die out, add dressing and bacon; return to heat and heat until just bubbly. Pour over the spinach and toss until the spinach begins to wilt. (Don't overtoss, or spinach will cook.)
Divide salad among 6 chilled salad plates. Garnish with egg and red onion, if you like. Makes 6 side-dish servings.