@jgroszko@tech.lgbt Oh no that's horrible.
The one that was plaguing me today was on a shopping site, but wasn't an ad. It's become fairly common in product views to have a set of images of the product, with a set of thumbnails below or alongside the current main image. The one I was viewing changed the image if you moused over a thumbnail, and popped up a zoomed version of the image if you moused over the main image. The net result was that placing your mouse nearly anywhere resulted in something popping into your view and covering up a sizable proportion of the page. The frenetic popping and unpopping made it easy to lose track of where your mouse pointer is, which led to even more frenetic popping and unpopping. Since I use a screen magnifier most of the time, the popped up stuff took up 90% of the available screen real estate. The net result was deeply frustrating, and I closed the page and moved on with my life.
The individual features are all useful. I like being able to see several different images. Being able to zoom the image is nice at times. However, the way they were all crammed together was poor, at least for me.