What affect does the condition of a cloth have on play?
Two physical properties describe the condition of a cloth: sliding friction (“slick” vs. “sticky”) and rolling resistance (“slow vs. “fast”). A “slick” cloth has very little sliding friction and allows the CB to retain its spin longer. For example, it is much easier to draw the ball on a “slick” cloth. A “fast” cloth offer very little resistance to rolling, so the balls roll much farther before coming to rest.
Cloth friction has an important effect on draw and follow shots at an angle. With a slick cloth, the CB persists along the tangent line longer before curving to the final direction, as demonstrated with speed changes in this video (a faster shot simulates slicker conditions):
In general, a new and clean cloth in a dry climate is usually more “slick” and “faster” than old and dirty cloth in a humid climate. A dirty cloth can also lead to dirtier balls, which can result in more cling. For more info, see the cling resource page.
For more information on how the drag effect of cloth friction affects various types of shots, see:
Cloth friction also has an important effect on CB swerve and massé shots. A slick cloth delays the curve, causing larger net cue ball deflection (the combined effects of squirt and swerve) for sidespin shots, and causing the CB to swing out more with massé shots.
For more info on the effects of humidity, see: humidity effects.
Also see the ball surface treatment resource page, because reducing CB friction has the same effects as a slick cloth.