Mr. Martin achieves the amazing accomplishment of being even more generic and bland than his counterpart Mr. Smith. He offers very few opinions on anything and pretty much echoes what everybody, especially Mr. Smith, says. Whenever Mr. Smith makes some sexist remarks, Mr. Martin is all like, "Yep, he's right." When everybody gets all upset about Mary wanting to tell a story, Mr. Martin readily agrees. In a way, it makes total sense when Mr. Martin replaces Mr. Smith at the end of the play – they're practically the same person.
One of the few differences between the Mr. Smith and Mr. Martin is that Martin manages to be even more forgetful than Smith. Smith may not be the brightest bulb, but at least he can remember what his wife looks like. It takes both Martins quite a while to remember each other. This hilarious and absurd process of elimination can perhaps be seen as a comment on the fallibility of memory. It could also be a comment on the subjective nature of reality. It forces us to ask, what would happen if the Martins didn't remember that they were married? Would that then mean they weren't? Much like with the Smiths, Mr. Martin's extremely shallow character manages to raise some deep questions.