People who order designs and display signs have a reason. Their objective is to have a sign that is eye-catching so people will read it. A business wants to sell a product or a service; a politician wants to get elected; groups want to announce an event and realtors are working to sell houses and other locations. If yard signs are not well designed or not put in visible locations then they won't be seen and the message will not be received.
The most important consideration when choosing colors for a campaign sign is to choose colors that contrast so that voters are drawn to the sign.While the sign will look professional, it won't get attention both because it will look similar to other candidates' patriotic-looking yard signs and there are other colors options that grab voters' attention better. Take a look at bandit signs from small businesses on the side of the road.