I hate lemon in tea as well. My tea order is always, "Iced tea no lemon," said without punctuation between because you've got to get it out quick before they move on to the next person. If the tea comes with the lemon stuck on the edge of the glass, I take it off in as conspicuous a fashion as possible and give it to my husband, who likes lemon. If it's in the glass, I send it back because, yes, once it's in there, it has polluted the whole glass of tea. All I want in my iced tea is tea, water, ice and sugar. I'll drink it without sugar if sweet tea is not available, but never with lemon. (I know I can add sugar at the table, but once the tea is cold, the sugar doesn't mix properly, and the waiter will only mess up the balance when the glass is refilled.)
My grandfather always said, "If I wanted lemonade, I'd ask for it."
I have gotten to where I can drink flavored herbal teas if I think of them as a spiced orange or spiced apple drink, not tea (which they really aren't anyway).