Most shock complaints I've had to deal with were actually the spring rate. Shocks keep the wheels on the pavement, springs support the weight of the rider/bike. When springs aren't right, there's bottoming out or excessively stiff rides. When shocks don't work, there's wheel hop, bad stopping performance, issues with the lean at speed, etc. since they perform against the unsprung weight of the wheel/swing-arm fulcrum.