***Spoiler alert if you haven't seen it!***
This is not an especially funny episode. Although it has a few good jokes it appears weighed down by the subject matter which I guess was more explosive then than it is now. That Cheers is a show from another time becomes very apparent by the regulars initial reaction to gay customers being in the bar and even the idea of it. They react by shying away, talking dirt and put fuel on each others fire of ignorance. It's crude and pretty much the same thing as racism. The gay theme could easily be switched to a skin color theme or something similar so one might say the subject matter is discrimination in general rather than just discrimination against gays. In this episode we see Norm and Cliff being homophobic jerks, Diane being the modern voice of reason and understanding, and Sam has to choose whether gays should be allowed in the bar but risk it turning into a gay bar (which to them apparently is a catastrophic scenario) or run them out to keep his regulars. Sam makes the compassionate decision and declares he doesn't want a bar where people don't feel welome. While it's nice to see common sense applied there are no great revelations or reasons why one should accept homosexuality, instead we through Sam get the message that you don't need to understand, all you have to do is look at whoever it is in question, recognize your shared humanity and accept that this is the way things are and then go on with your life and try to make it a happy life for everyone. A worthy message indeed.
PS! I can't seem to get proper spacing and line breaks here so I apologize for the wall of text this became.