Except when tapering for a competition, I've never personally had much luck with deloading. Usually, my deload weeks turn into just another training week. The difficulty is that, if you're like me, you hate to feel weak. To combat feeling weak, you train harder even when what you really need is rest. It is a vicious cycle that can very quickly lead you into overreaching, overtraining, and/or injury if you're not careful.
Some classic symptoms of overtraining are:
*Washed-out feeling, tired, drained, lack of energy
*Mild leg soreness, general aches and pains
*Pain in muscles and joints
*Sudden drop in performance
*Decreased immunity (increased number of colds, and sore throats)
*Decrease in training capacity / intensity
*Moodiness and irritability
*Loss of enthusiasm for the sport
*Increased incidence of injuries.
*A compulsive need to exercise
For my own training, the first indication of doing too much for too long is moodiness.... I have found that 5-7 days of complete R&R away from the gym (with maybe a smattering of ab or cardio) works just as well as a solid week or two of deloading.