[Kethra]

Well it is a conversation.

Usually one can tell from the context how a word is being used.

Example:

That pan is hot.
Geez, look at that guy, he's so hot. (shoot me for sounding like Paris Hilton, please)
The icecube is cool.
That's a cool idea.

Common sense really. No need to change the spelling around.

On the argument about cool's meaning being changed through time, becoming slang. That's how most slang comes about. However in these arguments, cool and kewl supposedly mean the same thing, (We're still talking about slang here, not the temperature meaning - ambiguity is usually dismissed with context.) thus the spelling differences are just... meh.