Slogans absolutely cannot go over one sentence and five dollar words such as "olfactory" should be avoided. Some rules are made to be broken; if there is a five dollar word that rolls up a few sentences of meaning in one word, go for it.
The one sentence rule, however,should be adhered to all costs. Simple slogan: just do it (Nike).Not simple enough slogan:Selling the Highest Quality Organic&Natural products (whole Foods).