Skeptics often argue for evolution and against creation by pointing to "bad designs" in nature. They say that if an all-knowing, all-powerful Creator made life, these "inferior" or even "leftover" features would not exist. However, a closer study of the frequently used examples of bad designs reveals a different picture. They typically fall into one of three categories predicted by RTB's biblical creation model:

1. Unappreciated good designs. These are revealed as good by further and closer investigation. Examples include the inverted retina in vertebrate eyes and the giant panda’s thumb.
2. Intentional suboptimization. In these cases, one or more aspects of the organism or system is not optimized so that the whole system or organism works properly. The 30% inefficiency in protein synthesis provides an example.
3. Decay from optimal. An initially well-designed system decays due to the operation of the laws of physics. Deviants of the universal genetic codes illustrates this process.  

Any example of a so-called bad design in nature deserves deeper study to see if it fits into one of these three categories.