That's the key to staying out of trouble!(SNIP)
Defective, worn-out bolts will snap before "snug" regardless if you're using torque-wrench or not. That's not fault of wrench or user. With experience, you learn to feel that "letting go" point where fastener doesn't increase resistance in-step with amount turned. Then you can stop and back it out before snapping. With or without a torque-wrench, beginners will go beyond snapping point because it will never reach "snug".