Has anyone ever noticed that there is a person in the porn shop that is wearing an identical raincoat to Columbo's? I wonder if that was done on purpose. (Also wonder if the gals standing outside of the shop wanted to see under his raincoat as well).

Yes, there was a similar scene in "Rest in Peace, Mrs. Columbo" (which was filmed just the year before), where Columbo enters the hotel looking for Carlton Chamber's bookie contact and a gentleman wearing an identical raincoat is walking out. I always enjoy Columbo's double-takes in these two scenes. Peter Falk was quite good at non-verbal reactions - a few which stand out are from "Murder Under Glass" (when Albert the Chef says he wishes it was Paul Gerard who was dead instead of Vittorio) and from "Sex and the Married Detective", when he is asked by several people in the office if he can help them out.

I always regarded it as a joke, about the association between Combo's "grubby raincoat" look and....a guy that leers at people in porn shops.

I was once asked to leave a public place for loitering (I was actually waiting for my car ride, who was a little late), and I think the beat-up jacket I was wearing contributed to that. No, it wasn't for the same reason as Ted mentions, but it's still kind of a comical story.

That raincoat could be a whole subject in itself. I get a kick out of the episode with Santini when Columbo is once again paired with Sergeant Wilson and he's wearing a different new raincoat but then as the plot continuous he goes back to his old one.

Funny! and another reason I find the scene in the porn shop amusing, besides the joke at Columbo's expense, is that over the years, more than one person has remarked that "raincoat guy" looks more than a little bit like me. And it's true. 

OMG Ted thats too funny!!!