Quite like the simple effects Instagram and similar photo editing software give you nowadays very easy to make a picture look really good :)
....It's also very easy to make photos look mirky and as if they were taken on a plastic toy camera! Too often Instagram = Instant Gimmick.
At the other end of the scale, some professional DSLR shots get so sharpened and Photoshop'd that they simply lose touch with all reality.
Of course both are valid but the art and skill is in recognising which version of any editing or post processing results in a satisfying image. I reckon that over 90% of Instagram images I see are yuk and barely 10% have the wow factor.