I agree that sometimes the labels don't match, however, when in doubt I generally use the labels on the products assuming they have had them "analyzed" and know of what they speak?
I also agree that given we are talking about spinach here, that 10 carbs (actually it's 5 carbs when you subtract the fibre) is too high??? Even on fitday the carb count for 1.5 cups of spinach is very, very low.
When all else fails you can try and contact the company to see if there would be any reason the carb count would be that high?
Good luck!

(see the spinach between my teeth?)
Froufy