Thanks for the question - Yes Ice Tea can go bad... if you buy commercial iced teas, you will find (or should find) an expiration date on the ice tea.
If you keep the tea too long, it will go bad and can really make you sick. Most good quality commercial ice teas have an expiry date somewhere on the bottle or can.
For homemad ice teas, we recommend that you make and drink the tea within 24 hours or it can go bad.
Don't take chances, bad iced tea can make you really sick.