Man the only reason weed smells and tastes like things are because of genetic phenotypes. In a random assemblage of Polycyclic Aromatic Hydrocarbons some will react with each other, in the leaf or resin, and a small molecule may break off and become air born. When these airborne PAH's enter your smell receptors they yet again react in a particular way in regards to its chemical makeup with the receptor, giving you the thought, image, experience of smelling pineapple. One variety that almost has a gasping for air, it smells so good. Me and my friends used to say, when you smell that its smells exactly like what you would think weed is going to smell like. Anyway White Widow has some of the most distinctive phenotypes in regards to smell I have ever encountered. But I digress that is why weed smells occasionally.
But no it is not possible to cross salvia to cannabis. Salvia is a sage and cannabis is a tree. You may be able to work with gene splicing and find a result down that path otherwise don't even hope. There are companies that make millions annually that sell genetically engineered plants, so don't ever think you thought of that first.
Peace