I think it can be sleazy if done subversively, however it can be a less-abrasive than a regular cold call if intention/purpose is stated up front. Finding the right person in an organization can be hard, and it's much less of a waste of time for all parties if you find the relevant person quickly. It would also be important that you don't give the impression that the person referred to you believes the higher-up referred you because they endorse you.