Another place where there are hidden carbs is with an item that has fiber. Many products will claim a low carb count but what they are showing is net carbs to entice us into thinking it's lower carb.
Net carb is total carbs minus the fiber = net carb.

I also pay attention to the sugar grams in a product like salad dressing. The total carb count may be in range but if it has straight sugar, I make sure it's very very low.