[bl4ckneon]

I second this. Linguistics and "slang" is pretty interesting in its own right. I believe that "cool" is more universally used. Usually smooth is used to describe an action that someone did, not really heard it being used in place of "cool".

(under 30 male, west coast USA perspective)

[eythian]

I tend to agree, smooth is IME also usually (but definitely not entirely) used sarcastically, when someone does something accidentally silly, like bumping into a glass door or similar.

(over 30 male, NZ)