When is balsamic just a cheap imitation of the real thing?

Good to know, from Good Stuff NW:

Bottles of balsamic vinegar on store shelves labeled "Balsamic Vinegar of Modena" are a commercial grade product made of wine vinegar with the addition of coloring, caramel and sometimes thickeners like guar gum or cornflour.

Authentic balsamic vinegar, labeled "Aceto Balsamico Tradizionale di Modena," is produced from the juice of just-harvested white grapes (typically, Trebbiano grapes) boiled down to approximately 30% of the original volume to create a concentrate or must, which is then fermented in a slow aging process which concentrates the flavors.