If a route is climbed very often then it can quickly become polished. This is where the rock becomes smooth as the friction of people shoes and hands wears it away. This can be seen in clear evidence on well travelled routes such as "Saul's Crack" (HVS 5a) on the Upper Tier of The Roaches, Peak District, UK. The retro bolting of a route makes it accessible to more climbers which will result in the loss of quality of the rock through polishing.