Unless you have x-ray vision, there is no way to tell. On Hondas in particular, it is very important to change the timing belt as recommended. Hondas use "interference type" engines, which means that the valves and pistons occupy the same space, just not at the same time. Result being, if the timing belt breaks, (especially at higher rpm's), you end up causing major top-end damage to your motor. Include 4 valves per cylinder, depending on the engine, (assuming you do not damage any of the pistons)and the repair costs can get really ugly. Better off to replace it before it ever breaks. An ounce of prevention is worth a pound of repair.