If there's one thing I've learned from making smoothies, it's how surprisingly potent certain fruits and vegetables are. Case in point: the most potent fruit I've used is watermelon and the most potent veggie is celery. What do these two have in common? Water! How can two things that are known for being full of water completely take over the taste of a smoothie?
Two other potent fruits I've found are raspberries and bananas. Now, I knew that bananas were potent enough to hijack the taste of a smoothie - which is why I never use them - but I didn't expect raspberries to do the same thing. Boy, a few raspberries goes a loooong way! I guess this is a good thing since when I use raspberries, I put them in the juice by themselves and attempt to pulverize the shit out of them before adding everything else. The fewer raspberries needed, the easier to get rid of those pesky seeds.
On the other hand, strawberries are surprisingly not potent. Despite their strong taste and smell, when you add them to a smoothie they seem to disappear. I add them to every smoothie I make mostly for bulk because they honestly don't add much flavor (which makes me sad). I suspect the fact that they are one of the fruits that doesn't have much sugar may play a role in their lack of flavor, but I'm not really sure.
Finally, as I've mentioned before, I found quite a difference in taste when you add spinach vs. kale. Unlike what I had heard, spinach really added quite a bit of flavor, whereas kale did not. However, I have found a workaround for spinach - cooking it. More specifically, I steam the spinach and then freeze it. For whatever reason, it doesn't add much flavor cooked. Go figure!