In photography post processing is essential.
Not applying editing or too much editing is bad.
Photoshop is on of those software for doing magic
in your photo, or ruing you photo if you are not skilled.

01.Feathered Edges

Fethering edge at extreme is so bad.
Just dont do it.

edge

02.Not Applying Lens Correction

Lens Correction is very important in photography.
Definitely nobody want to see distorted photo.
You can do this in lens correction in photoshop.

03.Color Cast

A color cast is an unpleasant color shift in a photo.
It`s produced by certain elements like shooting
with nd filter that produce color casting in actual image.

It can be easily be fixed in photoshop.
Image ->Adjusments ->Match Color ->Click Neutralize(Then Click OK)

04.Too Much Saturation

In photography one of the sins is oversaturated photo.
There is nothing worse than photo that is oversaturated,
all highlights, all colors are blown out.

satur

05.Too Much Contrast

Too much added contrast on a photo is overprocessed photo.
Let`s face it is bad as it looks, don`t do it.

contrast

06.Selective Color

Selective Color editing died in 90`s.
Nobady do this insane editing to attract attention.
It can be done in extreme situations, when you have
too much distractive elements in one photo.

For example distractive elements like concrete jungle like
New York City and one red van in the middle of the photo.
You can do this by selective color for the red van
and everything else to be in black and white.

scol

07.Crooked Horizon

There is nothing worse than crooked horizon.
Before you do the actual shooting, level your
camera for straight horizon.
Fixing in photoshop may be hard if the horison is not aligned in the camera.

crooked

08.Heavy Vignette

Extreme vignette is bad in any photo, no excuses.
Adding vignette fo photo to pop up is ok to certain level.
Avoid heavy vignetting at any cost.

vignete

09.Pulling The Shadows Up Too Much

Pulling the shadows slider to right too much is one big problem.
Especially if you use entry level dslr and bad noise reduction.
Actual quality of extracting the shadow from one image, depends
from in camera noise management, dynamic range.
Better quality cameras can do better with shadow recovery.

shadow

10.Not Doing Any Processing At All

No matter what camera you have, not doing
processing is bad as doing too much processing.
Do the post-processing in the limits of you knowledge.

11.Sharpening (using both sharpness and clarity)

To much sharpening in post-processing is bad.
The photo will be full with noise, unwanted colors.
Be gentle with this option.

sharp

12.Not Using Raw Format

Raw format offers ton of possibilities.
Shooting in not raw file will create totally not editable photos.
Be sure that you are shooting in raw format.

13.Super Moon Reality

Just stop doing this photoshoped super moons.
It looks unreal and obvious.
Especially if you make beginner mistake placing
the clouds behind moon, it looks terribly bad.

sn02

14.Liquify Tool

No need to speak out for this fail.
Just don`t do it.
If you can`t photoshop you muscles.
Than try the gym, but you will need decades
to achieve that photoshop fail.

liq

15.Not Using Noise Reduction

No doing noise reduction is same as too much noise reduction.
Don`t abuse this tool, use it wisely.