Recently I visited the Fotografiska museum in Stockholm. The major exhibition was Ruud van Empel's "Pictures Don't Lie" with stunning although eerie pictures. This is how the museum describes his work:
"From hundreds of photographic fragments, he compiles images that are genuinely lifelike in their appearance but conjure up a world that has never existed in this form. This paradisaical world is primarily populated by children, as the symbol of innocence, which is one of the major themes of his work. Despite their astounding beauty, these works are far from unequivocal, there is something not quite right: what is real here and what is not?"
Even as an amateur photographer, you need to decide to what extent you want to manipulate your pictures. With a vast array of tools you have all kinds of options, from Picasa to Photoshop and beyond. Since the camera and you do not record the same image, is it really to change the picture if you want to enhance the blue in the sky afterward so it becomes the colour you remember it "really" was?
However, already in choosing motives and angles we add our opinion to the picture. So maybe the questions is not whether a picture can lie but who's story it tells? Which story do you want to tell?