Truth in argument has two components, material truth or accuracy (correspondence with some external state of affairs) and formal validity (correct logical relationships among parts of an argument). Using fallacious arguments intentionally is a form of lying, just as much as intentionally saying things that do not correspond to external reality. Both are forms of deception, in which you lead people to false conclusions. Advertising is especially prone to skirting the edge of the law by means of implicit fallacy, such as the open-ended comparative --
i.e. advertising "New! Improved! Cleans 26% more!" (new could mean the colour; improved could mean the shape of the bottle; and without stating 26% more than what, the claim would be true even if it were 26% more effective than mud and worse than every other cleaner on the market).