OK I made a smoothie that didn't go well. 

2 carrots
1/2 c. frozen mango
1/2 c. orange juice
3 leeks (this is where I went wrong).  Had this been kale or spinach I think this would have been a winner.  Plus 3 was way too much.
ice cubes
I thought I had read that leeks were a good sub for leafy greens and boy was I wrong.  It wasn't necessarily that bad.  I think if I took out the fruit and made it a strictly veggie smoothie, I could have added garlic and tomatoes and it would have been great, like a V8 smoothie.  I had never tried leeks in smoothies and thought the "onion"-y taste would get overpowered by the orange juice and mango - NOPE.  But I hate onions, so my palate instantly pushes back on them.