Just to reinforce what Gabe said about the Morph Brush. It is very powerful and can do the basic things a dedicate sculpting program can do, except for very intricate work.

Aside from a poke-thru fix, which literally takes a few seconds once you get the hang of it, sometimes it is just easier to use the Morph Brush to create a character fit in a piece of clothing rather than go through the steps of Wardrobe Wizard and still have to tweak after that process.

First I use the clothing's morph dials to get it in the ballpark. Then use the Morph Brush's push and pull functions with a broad brush size to get it closer. Then I use smaller brushes and low magnitude for the final  shape, then brush over rough areas with Smooth. That is oversimplifying it, but it's the general idea. Spawn a FBM when all is perfect, then delete the Custom Morph you made in all the clothing's body parts (first set everything at zero and make sure the FBM works).

I only run into problems when the clothing mesh is too lo-res or the vendor has done something odd that prevents the brushes or the symmetry function from working properly. But most commercial meshes seem to be good quality.