Smell - the characteristic difference of acetic acid. It is very sharp and Shiba nose. Don't sniff the bottle with a concentrated vinegar close, bring it in 10-15 cm from the nose. If you are close you can smell fumes coming from the liquid, can burn the respiratory tract and problems will be very much. Try not to drip and the skin will burn.
Acetic acid burn. Pour some liquid into a little bowl and put a match, but be careful you can get burned. Combustion is about the same as the regular alcohol. As it evaporates it ceases. If ignition did not happen, you have either Apple cider vinegar or some other liquid or dilute acid.
Distinctive sour taste speaks for itself. But don't try acid directly from the bottle, you can get severe burns of the esophagus. Pour a teaspoon into a glass and dilute at least 20 parts clean water. Then can try, you should feel the sour taste and sharp smell. In diluted form it is used for making various sauces.
Unfortunately, the home does not carry out any experiments for a more precise definition of the substance. Therefore, other experiments leave for professional technicians. And, of course, do not drink the substance inside if you are in doubt. Acetic acid is very cheap, so better buy a new one than you'd get poisoned unknown composition.