You need to read the labels carefully and totally. Are there sugars in them? Remember there's alot of trickie words which are SUGARS. What's the serving size? What's the carbs in that serving. What is the fiber.
Suggest you review Low Carb Tips and Low Carb Tools. See the very top of this page in the ORANGE BAR SECTION. Also, suggest go to newbie section and read the helpful hints links.
As for myself, I find it CHEAPER, easier and safer to make my own salad dressings. I make a different batch once a week. Not only taste much better than anything I've ever bought from the store, but I know they don't have SUGAR and other garbage in them.