The left side shows the bad example and the right side shows the good example. A huge percentage of photography before was very flat looking, often with people in strange-looking colors.

A good lighting and a little set up can make a world of difference.

A poor lighting technique and retouching could make an outdoor look like indoors. And the grass look like a carpet.

A poor shadow effect can give the wrong impression. Like a pool is floating.

A good photography can easily be ruined by a bad retouch job and poor judgements.