Pink

While not quite as vile a color as urple or other Suvian colors, Pink, a lightish red hue, is often considered a Sue color, and hated, because of its sheer pinkness.

This, however, might just be due to the fact that if an Agent is especially blood covered from a mission, and they forget to use bleach for their whites when they do their laundry, they end up with a large amount of pink clothing to go with their black uniform.