The episode was set in San Francisco not Chicago. Ness wasn't as well known on the West Coast as he was in the Windy City and more than likely his picture hadn't been in any San Francisco newspapers. Plus, it was stated in the dialogue that the two gangsters he was spying on, Gregory Pindar and Griff Darden, had both been out of the country for several years. So the episode really doesn't require that much suspension of disbelief if you paid attention to the dialogue.
You tell em, boy. Of course, if you're looking to criticize, instead of just to enjoy the show, you can see this flaw and it might bother you. I saw the show when it originally aired, and loved it. I didn't sit and analyze details to poke holes and show how smart I could be- like the OP punk.
You are correct. Plus in that era there was no TV, no Internet, and Ness was not widely known to the very disparate world of thousands of gangsters all over the country. So the chances they would know what Ness looked like were minimal.
TTe TV series aired weekly and may give the impression that ness was constantly interacting wiht a closely-organized array of gangsters. That wasn't the case. My guess is that Ness's name and photo appeared hardly ever in the newspapers. Also the chance that these two gangsters were communicaing closely wiht Frank Nitti or Al Capone was mimimal.
So, as you say, one does not have to suspend belief, as that sarcastic poster suggested. Of course, if you are looking for flaws in watching the show, you could say that his was a minor flaw. It didn't affect my enjoymnet of that episode whne I first watched it (when it originally aired), not the second time when I saw it in a re-run.
I'm a huge fan of The Untouchables, but I have to say, when I first heard that Ness was going undercover as a crook with the name "Whitey Steele", I broke out laughing. Whitey Steele? Doesn't that name just give away that he CAN'T be a real hoodlum and could ONLY be Eliot Ness undercover?
Well, Stack does not look like someone who would be named "Whitey." Also, his story of having killed one of the hoods seemed questionable. It was not one of the better episodes. Still, it didn't bother me as it did you.