Combining switching and linear regulators
The output from the linear regulator will be typical linear - smooth and flat.

That's not to say that your circuit as a whole will be clean.  The switching frequency from the switching regulator can get into your circuit other ways.  There can be ground bounce or ground loops where the switching noise gets into your analog signals.  There can also be radiated interference from the switching regulator that your analog sections pickup and amplify.

Using a linear regulator to clean up after a switching regulator helps, but it doesn't get every thing.