Right, the Snapsis CSS Skin Engine is not a way to get "CSS Skins", but it's purpose is to make it easier for you to build CSS Skins, and it also has some pretty good examples of skins that use very few tables for layout.
The methodolgy behind the Snapsis CSS Skin Engine for DotNetNuke is to use CSS for displaying images as background images and the navigation is completly CSS, but for cross-browser compatability with a consistent layout it is better to use a table or two.
To me, the term "CSS Skin" does not mean "No tables", but if you use CSS heavily, including for positioning, then you will have less need for tables, especially embedded tables (tables within tables).
Using embeded tables just to get a graphic or navigation system to position the way you want is the reason that tables are frowned on by those who know that using CSS in those situations will be much faster to render and much better for globally applying style.
On the other hand, if someone tries for days and days to get tabular data to display using only CSS then they have way to much free time on their hands and are not using their available tools effectively. This would be akin to an artist only using one size of paintbrush, or a car mechanic only using a crescent wrench.
Anyway, I just wanted to give my take on what a "CSS Skin" is since the Snapsis CSS Skin Engine for DotNetNuke was mentioned here.