Sugar doesn't go off. It is a preservative. They've even stopped putting dates on sugars. The right sugar is important though.
how cheap cakes and cookies are to buy
Look at the ingredients. A cake make from sugar, butter, flour and eggs is much better.
Here are the ingredients for Mr Kipling lemon slices : Sugar, Wheat Flour (with added Calcium, Iron, Niacin, Thiamin), Vegetable Oils (Rapeseed, Palm), Glucose Syrup, Humectant (Vegetable Glycerine), Dextrose, Hydrated Lemon Peel (Lemon Peel, Water, Preservatives (Potassium Metabisulphite (Sulphites), Sodium Metabisulphite (Sulphites))), Dried Egg White, Whey Powder (Milk), Maize Starch, Concentrated Lemon Juice (contains Preservative (Sodium Metabisulphite (Sulphites))), Raising Agents (Disodium Diphosphate, Sodium Bicarbonate), Vegetable Fats (Palm, Shea in varying proportions), Tapioca Starch, Emulsifiers (Mono- and Diglycerides of Fatty Acids, Polyglycerol Esters of Fatty Acids, Soya Lecithin, Sorbitan Monostearate, Polysorbate 60), Flavourings (contain Milk), Salt, Stabiliser (Xanthan Gum), Preservative (Potassium Sorbate), Milk Protein, Gelling Agent (Sodium Alginate), Acid (Citric Acid), Colours (Titanium Dioxide, Lutein)
Lemon drizzle cake: butter, eggs, flour, sugar, lemon.