I've just read an interesting post by Roger Dooley, The Power of Positive Names. In his review of an upcoming study about the power of naming products and product categories (to be published later this year in the Journal of Consumer Research), Dooley gives simple but quite powerful examples.
It turns out, we are much more likely to indulge into cakes for breakfast if cakes are called muffins. In a similar way, we appreciate a dish of pasta, meat and vegetables if it's called pasta salad rather than simply pasta. And yes, a smoothie definitely sounds more healthy than a milkshake, notwithstanding the fact that it's essentially the same product.