Your car's paintjob is much more than a simple aesthetic consideration: the coat of paint over your vehicle acts as a protective barrier against moisture and the elements, preventing structural damage to the chassis of your car. Therefore, a damaged or otherwise worn paintjob can create real problems to your vehicle: understanding the warning signs associated with a paintjob that needs to be redone can help you catch it early, before these problems can manifest themselves.
The most noticeable sign that your paintjob is in need of a new coat is if there are certain sections of your vehicle that have a more faded appearance than the rest of your car. This is due to general wear and weather exposure, and points to the thinning of the paintjob itself, making it easier for moisture and wear to reach the body of your vehicle underneath. If you don't want to repaint your entire vehicle, be sure to color match the faded spots to the not-so-faded spots to ensure an even coat.
A step further than fading is when the paint begins to physically pull away from the body of your vehicle, peeling away in strips or bubbles that expose the underlying metal. Peeling will commonly occur after your vehicle has been scratched or otherwise physically damaged, since this will create an edge that will slowly begin to fall off of your vehicle.
If your car's paintjob is particularly old, rust may have already had the chance to set into the body of your vehicle. This is a particular concern, since rust can spread much like a disease through pieces of metal, disintegrating them slowly but steadily over time. If there is rust on your vehicle, you should head to an autobody shop straight away to have that rust removed, firstly, and then a new coat of paint applied to your vehicle, particularly the rust-affected areas, in order to prevent rust from setting in once again.
Finally, the last reason why you should repaint your car is if you are in an accident and there has been some sort of structural damage to your car. This is because the scratches and dents in your vehicle will be easily spotted, due to the damage to the paint, and also because such physical damage will open the door up for the body of your vehicle to begin to rust, compounding the problem.
For more information, contact companies like Sam's Automotive Reconditioning Center.