They have pungent aromas which are unmistakable. A little whiff won't hurt you, but if you get a lungfull, get fresh air immediately. If a cough develops, see a doctor. Dilute acids are relatively harmless. Soft drinks, pickles, and tomato sauce are all acid foods.
Acids taste sour.
Concentrated acids, on the other hand, are quite hazardous. They will cause acid burns on the skin, can blind you if splashed in the eyes, and can kill you if ingested. Some industrial drain openers contain concentrated sulfuric acid. If it can open a drain, it is not good to drink. If you happen to drink some, do not induce vomiting and head immediately for the emergency room.