This is a big idea in Carlos Castaneda’s books. It might also work as a skill to be practiced during this month’s moon quest. (click here).
As for substances in a dream, I’ve drank beer. I also assure you all that I am indeed 19 years of age (legal drinking age here in Canada) … also over 21, since this is international. 
You get what you expect to get in dreams, so I’d say that you would absolutely feel the effects. I imagine that someone who hasn’t experienced the true effect of something may have the SC make something up for them. To tell you the truth, I didn’t like being drunk in my LD, it sorta defeated the purpose and felt like low-lucidity.
Click here to read my Drunk Dream.