Great idea. I'm glad you actually tell them they're eating spinach. I'm sure it's AFTER they gobble down the smoothie. I really hate the old hiding/tricking scheme. If you "hide" all these veggies how will kids learn to like them? I do the tricking too, even with 50+ year old hubby, but honestly, can't they just learn to eat this stuff? It's not hamster brains or dung beetle. Just try it, you might like it. Think of the first person who ate an oyster. What were they thinking?! They're delicious though.
I think spinach got a bad rap with that mushy, grayish canned stuff. And then parents passed on their distaste to their children, so no one ate spinach. Fresh spinach is totally different. Probably the same with any vegetable you hated as a child. Try it again, cooked differently and you might discover you like it now.