Now that you mention it, it is these obscure
quotes that stand out in our minds, possibly
because they are mundane things we hear day to day.
We particularly remember that one because
the motel manager says it in a rather funny,
yes, I remember how he says it. But it is true what you say about remembering the mundane quotes because they are things we would say in the course of everyday. I find myself, that I use a lot of lines from Columbo, it is really funny sometimes how I can't get through the day without saying something to someone which is a direct line from the show.
Another couple of favorites in our house, both from "Negative
(1) It is cold outside and some is looking for their
coat, someone invariably says "that coat...that coat" (line from nun played by Joyce Van Patten).
(2) Someone asks someone else if they are eating some particular food...the answer is "that is the prevailing theory!"-quote by Mr Dolan played by Vito Scotti.