"On the internet," notes one pooch to another in that wise old New Yorker cartoon from 1993, "nobody knows you're a dog."

That is still true, nearly two decades later. At some point, you will be taken in by some kind of clown on the internet – whether it is an internet dating prospect who falls short of his or her description; a con man promising to reunite you with tax refunds or money in Nigeria; or, more likely, someone putting out false information in the hope that you will believe it to be true.

As a journalist, I've been fooled in the past by partial information on the internet – and corrected it fast; every other working journalist has had that experience as well. But there is a blind spot in journalists' ability to determine who is credible, and that blind spot is, apparently, Twitter.

Perhaps it's time to update that old cartoon for the age of Twitter: on the internet, it seems, nobody knows you're a troll.

Let's talk specifics. This week, there was the curious case of ComfortablySmug – aka Shashank Tripathi, a 29 year-old working in finance. Smug, as he was known, gained 6,500 followers over the past few years as an intelligent, self-aware young man inhabiting the persona of an internet troll: that is, someone who says something outrageous to provoke a response.

On Twitter, his real identity was hidden, though the essentials of his online persona were not: openly disdainful of – and yet friendly with – the press, active in Republican politics, working in finance, and strangely self-aware about his often abrasive online pronouncements.

Tripathi, who has over 6,500 people following his news alerts and commentary on Twitter, appears to have purposely sent out erroneous "BREAKING NEWS" tweets during Hurricane Sandy. He claimed that the floor of the New York Stock Exchange was under three feet of water (which nearly 650 people repeated on Twitter initially); that Governor Andrew Cuomo was taken to a secure shelter (when, in fact, he was on television doing interviews); and that ConEdison would pre-emptively shut down power to all of Manhattan (65 retweets).

Tripathi was well-known to regular followers as a largely friendly troll, and he was completely in character all night during the brunt of Hurricane Sandy. Among the trolling tweets that Tripathi wrote: fake tweets that he attributed to the official Goldman Sachs Twitter account, such as "in a city underwater, the vampire squid is king," and a tweet that he credited to the official Barack Obama Twitter account that advised people to eat their dogs.

He confidently declared, "Tomorrow I will begin to rebuild New York City in my image. After the storm, joined by an army of bodega cats, I will seek out the survivors."

In short, he was obviously a joker. A clear-eyed look at the entirety of his Twitter feed that night would have exposed him as perhaps not the best source of breaking news: a tweeter, writing anonymously, with a well-established taste for mischief. On any sane day, the ridiculous tweets – usually authored by Tripathi himself – would easily stand out.

But here's what made the difference: Tripathi's claim about the New York Stock Exchange was was shared nearly 650 times, during the height of the storm, largely because journalists and others with powerful credibility carried it across their Twitter accounts.

The reach of Tripathi's single tweet on the NYSE was so powerful that the National Weather Service repeated it, which then allowed it to make its way to the Weather Channel and CNN. With an hour, the national press was reporting this completely made-up statement as fact.

The blowback from there was complete: BuzzFeed thoroughly outed him with his full name, profession, picture, and even his entire history as an internet commenter. The reporter, Jack Stuef, also revealed Tripathi to be the campaign manager for a Republican candidate for Congress. New York Councilman Peter F Vallone Jr threatened to throw him in jail. A Twitter search for "Shashank Tripathi" reveals the kind of invective usually reserved for criminals and murderers, not stupid pranksters.

Tripathi's outing was inevitable: anyone using an anonymous name to bully or troll others should and will eventually be named. According to his latest tweet, the consequence for Tripathi has been to force his resignation from Wight's congressional campaign.

But the enraged reaction of many to Tripathi's prank was completely out of proportion to his actual offense. His claims were not, as some claimed, the equivalent of "shouting fire in a crowded movie theater".

For one thing, where was the theater? People in New York were largely trapped at home. Were they really going to run screaming into the streets, unable to handle the idea of the New York Stock Exchange being flooded? Were emergency responders going to stop answering calls to ferry over to the Stock Exchange to prevent water damage to the floors? Would people turn off their generators, hoping to save power for the day when stocks could be traded again? No, no and no.

As one fund manager at a $6bn hedge fund concisely put it on Twitter: "Is it really the end of the world if the floor floods? This is just getting stupid."

There were those who argued that Tripathi's pranks wasted valuable time that could have been used for storm response. But swatting down rumors is the cost of doing business for many companies; it is, in fact, part of the reason why big companies have Twitter accounts – to keep an eye on rumor-mongers and reputational damage. That is why they have spokespeople and social media managers, none of whom spend their time pulling bodies out of the wreckage. In fact, ConEd did respond directly to Tripathi and corrected him; he retweeted their response.

As for the NYSE tweet, It took about 45 minutes for Pat Kiernan, a beloved news anchor in New York, to point out that a live video feed of the New York Stock Exchange's floor showed it to be completely dry. But when Tripathi finally got to correcting his tweets – "NYSE DID NOT FLOOD" – his name had lost sizzle; it only got retweeted five times.

Here's the thing: while what Tripathi did was stupid, inappropriate, ill-timed and loathsome, the reaction to it was entirely out of scale to the actual offense. The truth is, Tripathi had a relatively small niche on Twitter. His influence would have been limited had not journalists on Twitter been desperate for information to share, regardless of provenance.

He was not the person who affixed those headlines atop legitimate news sources: journalists, who should have checked their sources and did not, used their power of the press to popularize the claim and bring it into people's homes. The decision to publish Tripathi's information was made by journalists, even when his persona and the nature of the information called for skepticism.

In fact, the first responses to his tweet on the NYSE, from non-journalists, were as follows: "That's bullshit"; "What are the sources for your links?"; "confirmed by whom?" and "you are a liar."

Tripathi, as an internet troll, was completely in character, and he had no responsibility to the public. But journalists do have that responsibility – and so, if Tripathi's silly tweets made it into the national press, it is the national press that is, at heart, to blame for not protecting journalistic standards as well as they should. It is a matter of a few minutes to call a spokesperson or check a live camera, and that is what journalists get paid to do. Producers or editors should not rush information to air or print until those calls have been made, and answered.

Any trained journalist could never imagine running to an editor or producer with the claim "I have information from someone I don't know on the internet!" and getting a green light to publish.

Journalists may get fooled anyway (God knows we do), but the responsibility to readers, listeners and viewers is still in our hands – not just in the hands of a reporter or editor, but of the entire journalistic teams that report and package and deliver news. When Twitter pronouncements make it to TV, the web or papers, it is journalists who are the gatekeepers who allow that. Even in the internet age, when information is easier to obtain, individual judgment counts: judgment on who to trust, the character of sources, knowing their agendas and history.

Anyone who read Tripathi's tweets, armed with that context, was not likely to have been fooled.

Most odd, however, is the underlying assumption, by those over-reacting to Tripathi's offense, that he violated some kind of internet code of honor. That makes zero sense. The internet has always been a place of the roiling, squirming guts of the information economy; it has never been a pure and inviolable place of absolute truth and reliability. People will lie; they will make mistakes; they will provoke and misrepresent and they will publish before they have complete information.

The job of professional journalists is to sift through that. And when we get mad at others for fooling us, we should also be mad at ourselves for fooling our readers.

• Editor's note: this article originally stated that Tripathi was a hedge-fund analyst (information via Buzzfeed); his specific job title and role is disputed, and not confirmed. The article was amended accordingly at 5pm ET on 31 October 2012