Caked-on salt stains, dirt, dust and grime can leave a thick buildup of residue over the windows, not only impacting the exterior of the home but also the amount of natural light that filters inside. Ignoring this residue can create an unpleasant and unwelcoming interior, making it look dark and unkempt. If your windows have been neglected for a long period of time and have become an eyesore, it’s time to call in the pros.