Sometimes you just can’t wait for better weather. In this example, the shoot had to happen on a Sunday, between the random storms that were forecast to last another week.
It’s not simply a matter of pasting in some blue sky, white balance and color has to be corrected as well. While a critical eye will almost always be able to detect a “shopped” image, most casual viewers will not. The majority of humans see photographs, but they don’t actually *look* at them.
So what’s the one major “flaw” in this image? It’s a dead-give-away that this image was not shot on a typically awesome Texas spring day.