The 5th definition of smooth in Macmillan:
showing disapproval relaxed and confident in a way that usually persuades people to do things. This word shows that you do not trust people like this
Steven's a bit too smooth for my liking.
a smooth operator (=someone you cannot trust)
However, I have run into examples like this:
We need to be really smooth in the meeting today if we want to close the deal.
He’s smooth! Did you see how he just got that girl’s phone number?
It doesn't look like smooth is used in a disapproving way.
What do you make of it?