Owning the ability convey a particular message in a brief but comprehensive manor, evidently, is pretty important. The best examples of this are usually successful due to their simplicity, essentially taking a familiar subject and turning it into something unexpected, yet, understandable. The kind of designs that seem so obvious you almost feel like a fool for not noticing them earlier. I'm imagining the satisfactions you experience when somebody cracks a witty joke — it simply works. It's intelligent, quick to grasp, doesn't baffle and isn't literal in the sense that it deadens any excitement.
A recent lecture by Gary Neill explored creative techniques including substitution, inversion, surrealism and exaggeration. Stemming from this I've collated some examples that successfully combine the former and creative wit. Some overlap in their technical approaches, others fall outside of these categories, however, all are results of great artistry.
Combination / substitution
Exaggeration / USP