Of course, not all advertising is untruthful. However, all advertising is, by definition, manipulative. The whole point of advertising is to persuade people to buy a certain product. In other words, advertisers are trying to manipulate consumers into buying their products.
Advertisers use a number of techniques to manipulate their audiences. One of the most common is to show some idealized lifestyle or situation and imply that anyone who uses their product will automatically share that lifestyle. In the US, beer ads tend to imply that using their product will give a person a fun lifestyle with lots of interaction with the opposite sex.
Another common technique is implying that something bad will happen if you don't use the product. We see this in the US with home security systems. Their ads imply that your home will be invaded and your family harmed if you don't use their product.
In these ways, advertising tends to be manipulative and it tends to at least stretch the truth in ways that will persuade people to buy a certain product.