I'm seeing these with more frequency, the kind of thing where we're promised 10 Hottest Megan Fox Photos or 15 Best Serbian Horror Films but instead of a full list we have to click through all of them to even see what they are. Now the Fox Photos yep that will be clicked but most of us are going to start snoozing for other slideshows.
Recently I found one that shows what a bad idea this is. Foods Your Dog Should Never Eat sounds like it should be very important if you want a healthy, happy dog. But there's about 18 of these (the rest of the 27 slides are an ad and some further explanations) which means not many people will get to an unexpected one like #12 Persimmons, Peaches, and Plums because they will have lost interest around #6 or #7. (Well I lost interest around #2 but I'm guessing people who actually have dogs will be a tad more motivated, at least until they see it's mostly familiar stuff.)
So the slideshow design undermines the entire point of an article such as this. What most readers need is the full list and quickly find things they don't know or maybe more info on ones they weren't sure about. Instead the slideshow forces needless and counter-productive interaction.
But while I'm on this page might as well point out that the design clearly shows how little interest WebMD has in this article anyway. The actual text is far smaller than the accompanying photo, in fact is smaller than the adjacent advertisement. Looking at the entire page the text isn't immediately obvious but almost an afterthought (which might in fact be true).
The article itself doesn't live up to the title. The section about not eating raw eggs for instance is very clearly not a "never" item and the parts about sugar and fat are just ridiculous (and also not even remotely a "never"). So we go from genuine warnings about dangers at the start and end up with a cliched diet with fruits, vegetables and cooked rice, just the sort of thing that people who don't enjoy food push in the mistaken belief that it's more healthy.