Why is the salad dressing bought outside sour, while the salad dressing made in the bakery has only fragrance ~ is it a different sauce?

The salad in the bakery outside is not really a salad. Personally feel very greasy! Carrefour's own salad dressing is sweet, a bit like outside! As for Le Jia salad dressing, it should be less delicious than Cupid and Kraft, which is natural! Cupid's salad dressing is sweet in red and original in blue, not too sweet! But I personally don't like red. It's sweet and disgusting. If I eat too much, I will feel uncomfortable. Of course, everyone has different tastes! Kraft's salad dressing is good and rich! !