ironic effect is, of course, communication all by itself.

My use of emoji in messaging applications is primarily limited to quick rebus-like reaction replies to meme images, a quick and dirty reaction to a message in slack expressing some vague emotional response, or making complicated fart-jokes with my partner that rely on a lot of out of band information.

(i also use IRC on the daily, and have been known to use emoji there too, so these communication forms are not disjoint)