This can actually be a big factor in the safety of your flight,
Cited from the FAR AIM:
- Windshield Conditions. Dirty or bug‐smeared windshields can greatly reduce the ability of pilots to see other aircraft. Keep a clean windshield.
- Visual Obstructions in the Cockpit.
- Pilots need to move their heads to see around blind spots caused by fixed aircraft structures, such as doorposts, wings, etc. It will be necessary at times to maneuver the aircraft; e.g., lift a wing, to facilitate seeing.
- Pilots must ensure curtains and other cockpit objects; e.g., maps on the glare shield, are removed and stowed during flight.
It is clearly denoted that anything that obstructs visibility can potentially become a hazard and safety caution to the flight. It is important that your windshield and windows all around the cockpit stay clear. It’s very easy to mix up small bug particles with actual aircraft approaching. In addition, the opposite can happen, ever get complacent with a bug on the window? Well, there is the potential to mistake an aircraft approaching as a bug on your windshield.
All in all, as the Pilot in Command (PIC) it is important to make sure your field of view is absolutely clear of obstructions, cleaning your aircraft is a big part of making sure that stays true.
Pride and appearance
As we have noted before, owning an aircraft can be one of the most rewarding experiences. In addition, it’s probably one of the most expensive additions to your lifestyle. You want to take pride in your investment, and you want to make sure people who also see you understand that you enjoy your aircraft. Having pride in yourself and your aircraft means that you are actively working to make sure it looks 100% under all conditions!