I drink my tea "Red Rose" brand only (I'm in Canada) and I add a splash of evaporated milk - no sugar. MMMMMMMM....so good with a cookie (or two)!
I really think the flavour of tea, coffee or any water based beverage is the water. I've had the same brand of tea at other places besides my home and it just doesn't seem to taste the same - but then I filter all my water so it's pretty pure water that I'm starting with.
Do you "brew" your tea or use a tea bag?
Linda