What types of systems have been proven accurate

Laser-Guided bombs were used in Desert Storm and Afghanistan. One story told of a US pilot flying in the Afghani desert, he spotted a armed group moving along the desert on camels, he reported to his commander and pointed the laser on the group, a few seconds later, there were a few less terrorists in the world.
Laser-Guided bombs can literaly drop a bomb through an open window, during Desert Storm a bomb could land within 15 feet of it's intended target, this has been changed so that bombs could even drop through a hole in a roof. What systems previoulsy thought to be accurate aren't?-----Are there ways for the enemy to reduce the accuracy of a system?