Common symptoms of overtraining (the first 4 are the ones I think are the most consistent signs):
failure to recover between workouts
you stop making gains, or WORSE, you slide backward in gains
lethargy and fatigue
when you work out you don't feel l ike you're getting "pumped up"
soreness in muscles and joints
injuries to muscles and joints
decrease in motivation to work out
loss of appetite
insomnia, moodiness, illness, decreased libido
It doesn't matter whether you're on steroids or clean, pay attention to these things.