Question: The 5th definition of **[smooth](http://www.macmillandictionary.com/dictionary/british/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?

Answer: 
Yeah, I think the dictionary is applying negative connotations inappropriately here.

I agree with the *relaxed and confident* definition, but leave it at that; it can be used for either good or bad purposes.
Really, the word in these cases are perceived from a perspective.

Just to make a case and build my argument.

The definition you provided would be more like a con artist.
The example you gave below is more like a negotiator.

Given that both a con artist and negotiator do essentially the same thing, persuede people, the context and stigma related to the words themselves essentially create a 'good' and 'evil' connotation.

For the word smooth specifically in your examples, it is purely based on context and perspective. It carries a 'bad' undertone, much the same as the word 'sly'. However, it is not inherently 'evil'.