31 The "empty tables" line is from "By Dawn's Early Light," referring to the enrollment being down at Haynes Military Academy.

32 The "twelve times a month" line, as already mentioned, is from "The Most Crucial Game."

33 I belive the "not as dumb" line is the true quote though not sure of the episode.

I see #31 and #32 were figured out right away. But I'm happy to see that #33 is puzzling everybody who humours me by playing along with my little Columbo games. It is truly an honor that the smartest Columbo smarties of them all haven't gotten it. Not that there's anything the matter with that. Come on Cassa, David and Paul. You too Great Santini (OH Great Santini... whereever you are!)

OOOOOhhh....is there a hint in that Headache???? You mention honor....A Matter of Honor???
This is torture!!!!
Well...if there wasn't a hint in your post, then I think it is high-time you gave us one.....we are floundering here. And I aint talking fishies!!!!

Or maybe How to Dial a Murder??? Games were mentioned a lot in that one...and you mentioned games in your post.
HELP!!!! You're killing me!!! I can't even figure out which is the real quote!!!

Isn't there a strong hint that it is from the Great Santini episode, Now You See Him. The quote about being not much to look at (the first one) seems to me as though it could have been said to the Great Santini...

You see what he does Paul?...do you see?....Headache comes in and out of his cave and then proceeds to leave us in the lurch.....torturing us to the bitter end!!!
I thought about Now You See Him...great answer...but where and when?...I don't know.......Headache!! the torment must end!!

The answer to #33 is:

"Well, there you are sir. You see, I'm not as dumb about these things as I thought."

Yes, it comes from "A Matter Of Honor". Columbo says it to Luis Montoya while the two of them are in the stable discussing the sort of "stick-thingy" that victim Hector Rangel would have had with him out there in the bullring.