The answer to 'window filthy' is that there are several common causes for dirty windows, including dust, grime, hard water stains, and streaks from improper cleaning. Symptoms may include a cloudy, hazy appearance, visible dirt and debris, and an overall lack of clarity.
For DIY solutions, start by using a squeegee and a high-quality window cleaner to thoroughly clean the glass. Make sure to clean both the interior and exterior surfaces. If hard water stains or stubborn grime remain, try using a vinegar or baking soda solution. However, if the windows are excessively dirty or difficult to access, it's best to call in a professional window cleaning service for a more thorough and effective cleaning.