Just the Sahara, not the Sahara Desert, since Sahara means “desert.”
Saccharin is the sweetener, but saccharine is the word for “sugary” and can be applied to someone’s nature or speech as easily as to a food.
Sacrilegious doe not contain the word “religious” and, therefore, should not be spelled “sacrelegious.”
And, despite all the times one sees it misspelled, it’s “salutary” not “salutory.”