Who told you lying visually is okay? If you send someone a picture of the car you’re trying to sell them and you use it to close the sale, and they pay you only to find out it’s not even the car – the car you showed them is nothing like the beater you’re trying to foist off on them – that’s definitely a lie! And it’s so far from okay you could probably be done for fraud. All they’d need to do is show the nice car picture you sent and the sorry-ass car you delivered as-if.
Thing is, humans are very visual creatures, yet most of the specific meaning content we convey is done with words. Few liars carry around visual aids with them. Gestures only convey so much. Nor is it likely to bolster your case if you break out a pad of paper and pastels – the strategy is so unusual its peculiarity alone would arouse suspicion.
Words, though, are our meat and métier. We’re used to describing reality and receiving descriptions of reality in words. It’s usual; it works. We’re most of us pretty used to receiving untruth in words, too. We’ve had to acquire a facility with telling between truth and falsehood, preferably by close comparison with reality.
So it’s not that “lying visually is okay.” It’s simply that it hardly ever comes up, and so comparatively fewer words are spent describing it, warning of it, complaining of it. Lying is lying.
Lying is any deliberate (1) untruth (2) conveyed in an attempt to deceive (3). Three things, all that matters. What’s conveyed must be false (2), the person conveying it must know it’s false (1), and they must be conveying it with a goal to trick (3) you that it’s true.
Anything that meets those criteria is a lie. It doesn’t matter how you convey it. It’s just that as a practical matter, words form the readiest medium for meaning, for truth, for information. As a result, most lies are conducted by means of words. It’s purely a convenience.