I must say that I used to love Red diamond tea but it's often very inconsistent. It doesn't seem to matter where I buy it one never knows what one will get. Like others here I have encountered some that was great and others that were undrinkable.
One common factor seems to be that if the jugs have have the screw type top they're usually okay. If they have the the melt on type top often used with milk jugs there's a good chance they will be nasty.
If I go to say Walmart (applicable to other stores too) to buy Red Diamond tea they may have a mix of screw and melt on type caps. What's with that? ARen't they from the same bottler? Why do they constantly change cap styles?
When the tea is from a good batch, it's fantastic. But should you get a bad batch, it's nasty.