I have seen and purchased not one, but
several teas that could fit this category. The first one was several years ago, and it was my mom who bought the tea, but I drank some so I guess it counts: "chocolate hazelnut truffle" flavored tea. It's in quotation marks because it tasted like...well, imagine the worst, stalest, most burnt, fakest-tasting hazelnut coffee you can...now pour that into a cup of really sub-par black tea. That's what it tasted like. I took two sips and gagged.
Next up was artichoke tea. Now, I love artichokes. LOVE them. But...to eat. Not to drink. I found this out the hard way. I drank tea made from a vegetable and it tasted like peanut butter.

And not in a good way.
Finally, some Vietnamese gourd tea that I got at the Asian market near my school. Holy moley was that stuff vile. I should have just stopped when I smelled the liquid. It was like a combination of composted vegetation, sweaty gym socks that have been left in a locker for a month, and fertilizer.
...So of course, I drank some. It couldn't be as bad as it smelled, right? Well, it was. Then I thought: AHA! Sweetener! It just needs a little honey. That can't make it any worse.
Except that it did. Ohhhhh goodness. It did.
Basically the only good thing that tea did was give me a story that I really enjoy telling.
Anyway, the tea I drank today was wicked... Wicked good! I've been drinking very yummy bi lo chun all day, with a lot of iced green tea because we're still having a heat wave. Green tea is so nice and cooling, even when the tea is hot.