As a relatively inexperienced photographer compared to most of the people who contribute to this forum, I hesitate to be critical of the pictures that I see here because I don't feel qualified. However, there are a few places where I generally seem to have a different opinion to the majority.
Many of the images that I see seem to me to be over-processed. Often, the saturation seems to be too much, giving a rather garish look to the image. This is subjective and could depend on the monitor that is being used, of course.
Another issue is sharpening. This is another subject that I am trying to understand and I tend to not sharpen my own pictures enough or properly. However, when I look at others and sometimes my own, I see that sharpening has produced some unwanted effects. There is the halo that is commonly acknowledged but another that I have not seen mentioned is with textured things. For example, sharpening the image of a tree with small leaves seem to make the texture too granular where a softer look would be better.