You know what your goal should be with marketing? To make your advertisement so interesting that the user forgot that it wasn’t why they came there in the first place.
This post on Content Marketing Done Right is a good example. There’s one of those ads on YouTube – where you normally sit there waiting for the ‘skip ad’ button to pop up. Except, saith Chris Brogan, this ad is produced so well and hooks you so thoroughly that it’s tough to stop watching it.