Salad Dressing Stains. To remove salad dressing from your clothes, you can try rubbing the stain with a liquid enzyme detergent, such as Era, then soak in cold water for up to 30 minutes or until the stain is removed, rubbing the stain lightly with your fingers periodically during soaking. If the stain persists, try saturating the stain with a laundry presoak and let it sit for a few minutes, then rinse.

Tomato Stains. To remove a tomato stain, try using an enzyme pre-soak spray. An enzyme pre-soak product is a stain remover that contains an enzyme which digest the stain in the same way that your body digests food. Two commercial brand names of this type of product are Biz and Axion, although others are also available. When purchasing one, make sure it says enzyme on the label, and follow the directions.

Spaghetti or Tomato Sauce Stains.
Unfortunately, heat sets in spaghetti stains, so if you have put them in the dryer they are going to be difficult to get out. Although it is tempting to wash them in hot water, cold will work better. The only other stain treatment that you haven't already tried would be dry cleaning solvent. You could also try placing the stained item in the sink with cold water dripping on the stain. Leave overnight, with the drips falling directly on the stain. This should loosen the stain.