Edits
It is about the right amount of editing in order to preserve the feel of a track while certain dropouts might occur distractions and therefore will be removed.
In general, less is often more...

edit

Drum to Midi Conversions
Already recorded Drums can be replaced with high end recordings of top of the edge instruments.
Here it is also important not to find the best but the most suitable Sounds.

Voice and Speech Correction and enhancements.
The right cut to transport information without irritating the listener as long as this is not your intent.