Tamarind is nasty. As is durian. When I was in Thailand everybody was like, "here tastes this wonderful fruit that smells like old unwashed feet, smells like hell, tastes like heaven" and ya know what? That shizzle tastes like it smells. Old feet. Gross. Any concoction, no matter how watered down, that contains either I'm more than happy to steer clear of.
Agree on the durian, but I'm ok with tamarind in certain forms. Don't want to drink it as a soda though. My wife is Thai, we've visited her home twice, and I've eaten it right off the tree in their backyard. In it's freshest form it's not bad, just a bit tart but still sweet. A lot of Indian restaurants around here serve tamarind sauce as a dipping sauce with their naan and that's fine too. Now, look around at asian and indian markets and you'll see squashed bricks of it, outer casing and all, wrapped in plastic, and yeah that's not too appealing.
Durian though.... yeah I agree. And, my wife loves it. Luckily it's not in the house that often. She actually had me try some durian ice cream which wasn't TOO revolting, but even that tasted off... and I'm a big fat bastard so if I won't eat the ice cream that's saying a lot...

I don't recall eating a single thing there that I would consider "gritty" though, and we spent 5 weeks there total across 2 trips, but I was eating mostly home cooking so that probably made a big difference.