One read of the ingredients list should give you a pretty clear answer:
Ingredients:[FONT=myriad-pro, Helvetica Neue, Helvetica, Arial, sans-serif] Water, Spinach, Sunflower Oil And/Or Canola Oil, Red Bell Peppers, Water Chestnuts, Whey Protein Concentrate, And Less Than 2% of The Following: Onions, Modified Tapioca Starch, Salt, Sugar, Natural Flavor (Including Soy), Lactic Acid, Vinegar, Garlic Powder, Datem, Yeast Extract, Sodium Polyphosphate, Monosodium Glutamate, Potassiuim Sorbate, Xanthan Gum, And Citric Acid. Contains Milk And Soy Ingredients.[/FONT]
[FONT=myriad-pro, Helvetica Neue, Helvetica, Arial, sans-serif]Not just that, 2 tablespoons has 52 calories and 4 grams of fat. Most people put 2 tablespoons on a single chip!
If you like spinach dip, you can really easily make your own by mixing thawed frozen spinach into fat free sour cream or greek yogurt. It'll taste the exact same as the Tostitos dip but be much lower in fat and calories and it'll have a 2 ingredient list. Sourcream/greek yogurt and spinach. [/FONT]