Silicones are in many products, from polishes to dressings. However, there are good and bad silicones. The bad ones to stay away from are solvent based. These solvent based silicon dressings are usually a clear gel. The water based dressings are usually a milky white liquid.
The solvent based silicone dressings can remove the protective waxes on tires, thus turning them brown and can cause side wall failure. The sling they produce can also stain paint which will require a repaint to fix. Sometimes that wont even fix it, as it will come through the new paint. These dressings can also remove the plasicizers in your dash, etc., which will in turn cause your dash to turn a white chalky color.
Silicones in paint can also give you SEVERAL problems when trying to polish it, or apply waxes/ sealants.