When I first discovered this tool in Photoshop, it was in connection with making a person slimmer in a photo. Sure, wouldn’t we all like to do that but the applications were limited and often obvious that there had been a touch-up. I also saw some applications in manipulating flames and smoke, but that too was limited.
So I went about my business without giving the Liquefy filter much thought.
The revelation came when an art instructor suggested using the Liquefy Filter to manipulate drawings for clients to see a variation on a theme without having to re-draw each and every drawing. Genius! What a huge time saver. Now when I see that the cheek is too pronounced or the one eye is lower than the other I can just use the liquefy filter and change it.
Of course if you have to Liquefy too much the pixels get distorted to the point the that lines have to be redrawn but the sketch is still there and the Liquefy helped to show where it should be as opposed to where it was.
For the artist, the Liquefy Filter has more uses than the average photographer, I would think. Try it sometime.