In this article, Steve Smith rants, and commenters add more fuel to the fire:
Along with eyeballs, time spent, content and ad dollars, the clutter and crap that has made the overall desktop Web experience a horror show had gone mobile too. Too many publishers are so frantically chasing monetization that the overall UX is degenerating quickly. My main pet peeves:
Native Run Amok: Publishers are piling on so many different modes of native ad monetization now, that the one-column mobile feed is cluttered and editorial voice is unclear.
Intrusive Ads Are Becoming Obstructive: a.) in-feed mobile ad units that hijack the basic scroll gesture. b.) microscopic Close buttons that are designed to be missed or to trigger the ad click.
Persistent Banner Obstructs Navigation: In Safari, the Back/Forward menu disappears when you start scrolling a Web page and is reinvoked by a gentle tap. A bottom-lying persistent banner confuses the user, who risks clicking into the ad rather than the menu.
Banners Are Not Scaling: As often as not, ad units look poorly sized in. Even large square units carry microscopic information. Likewise, banners scaled to a mobile are making their way onto tablets. So you get a ridiculously small ad unit combined with creative that is too small even for the mobile phone format, on a larger screen.
Ad Clutter Is Real: Sites are stacking their house app ad on top of a standard banner and then following it with a sponsored post. One article refers to house app interstitials as Kanye West-style hijacking:
Kanye West’s hijacking of Taylor Swift’s big moment:

Kanye-style hijacking of the UX:

A Kinder Way of Delivering the App Offer:

“Responsive” To What? To Whom?: The components of most sites make a lot more sense in the multi-columned desktop or tablet format. When stacked atop one another they feel like a random content pile-up.
Why It’s Hot: We’re buying more mobile inventory everyday; following the eyeballs, time spent and content…and landing in the middle of some very frustrating consumer experiences. We can talk to partners about concerns and exercise more caution when considering ad placement, as well as can help our clients to develop more satisfying user experiences for their own mobile site visitors.