I think most supplements are safe when used as directed. The food we purchase at the grocery store today is so over processed and full of additives that unless you cook from scratch, can your own foods, and use only fresh fruits and vegetables, you are going to come up short on nutrition. I don't use supplements but I would probably feel better if I did. I should also be taking advantage of my gym membership but I'm not doing that either. Shame on me!
A good diet and exercise are important but I don't see any problem with a person using supplements, as long as it's in moderation and they're legal. Moderation is the key to most things in life whether it be tanning, supplements, wine, chocolate, etc.