There's an article on Slate about those ads: http://www.slate.com/articles/business/moneybox/2013/07/how_...

Basically, the trick is "weird" because it's not too positive, so as not to make it sound false and unbelievable, not negative either, and uncommon enough to attract attention and pique interest. Of course, overuse of the technique desensitizes the viewers and it will eventually fall out of favor.