Because you can't taste it so well when you can't smell it - like holding your nose to take medicine. Coke tastes better with a lot of ice because this also helps hide the flavour. Putting lemon in further masks the taste. Ideally, don't drink the foul stuff at all and you will enjoy it at its best.

If the Good Lord had intended us to sully our systems with coke He would not have given us tea.