"Class C" uniform is not really an official uniform designation. It simply refers to wearing the Red Paoli 1 Shirt and whatever other clothes a scout wants. It maintains a level of uniformity without restricting the scouts either in physical comfort, personal preference, or versatility of clothing.
At the CabinEdit
Class Cs at the Cabin are very common and most of the time it is the choice of the scouts deciding to wear them rather than the instruction or suggestion of the leaders. Scouts will often wear their T-Shirts at Patrol practices, sleepouts, football games, work days, and Eagle projects.
It is highly encouraged for all scouts to wear their Class Cs at Horseshoe whenever leaving Lisle. That means Merit Badges, meals, and camp-wide events. It helps represent the Troop, make Paoli 1 visible to others, shows solidarity in our group, and also aids with keeping the group together (especially at games). It is quite a site to be walking the camp and seeing groups of red all over the place. Water Carnival sees Class C accompany bathing suits when the Troop treks to the pool to compete.
Some trips like the BSA High Adventure Bases require formal uniforms but most Paoli 1 trips have no such requirement. Still, scouts are often told to wear their red shirts especially when traveling to and from the trip location. It is easier to keep the group together and watch for any stray boys when everyone is in uniform. It also makes the Troop more presentable and representative of the Scouting movement to the community.