Native Ads in the Navigation

One of the hottest topics in digital media right now is viewability. Advertisers want their ads to be viewable to their audience and do not want to pay for ads that users did not see. Publishers have been taking many steps in order to achieve this. One of the ways is by making unobtrusive native ads above the fold.

Here are two examples from different publishers:

Edmunds:
The native ad for Edmunds appears in when a user clicks the "Make" tab in the navigation menu. In this case, it is the 2014 Mazda 3 ad. The ad continues to display as the user picks a model and year. This is a great example of giving the advertiser high visibility and adding value to the user in an unobtrusive way by suggesting a new car that they may not have considered.

Cnet:
See if you can spot the native ad. Hint: it's above the logo.

BBC:

In BBC's navigation bar, one of the tabs was presented by an advertiser.

BBC Landing Page:

The Page is sponsored by the advertiser.

New Yorker
The leaderboard ad appears like a flash in the pan in the navigation section of the page when the user is scrolling or refreshing the content.

What do you think about ads that are added to the navigation menu? Is this a good solution for viewability?