Quality honey is my go to for getting though bad teas. A strong rich honey will mask a lot of unfavorable flavors.
This is my favorite Honey for any occasion.
Me personally though, I wouldn't bother salvaging decaf teas as they are almost always treated with chemicals to get them decaffeinated, which, concerns me more than the caffeine itself. (I am also extremely conscious of my caffeine intake).
But if your situation favors drinking those teas, give the honey a shot!