People have frequently visited this site and deposited hostile comments, usually without bothering to read the evidence first. Occasionally, I have answered these criticisms, which is usually a mistake. The debates can get very heated, on both sides, and the critics are usually totally unwilling to take the evidence on board or deal with it in a rational way.
One of the main criticisms tends to be that Cassidy was honest and that my depiction of him as a con-man and a fraud is misplaced. According to these people, Cassidy’s book of fantasy etymologies was basically well-intentioned, an interesting attempt but Cassidy ‘overreached’ a little so the core of truth has to be sifted out of less believable material. This is utter nonsense.
As I have shown on this blog, there is no core of truth in Cassidy’s work. Cassidy certainly tapped into a number of common folk-etymologies linking English words to the Irish language and he probably obtained these through an Irish-language learners’ forum he used. This gave him words like twig and dig, say uncle, longshoreman, phoney, pet. All of these have been dealt with in great detail and have nothing to do with Cassidy. (Some of them like twig from tuig and phoney from fainne are certainly possible, while others like longshoreman are very unlikely.) He then set to work looking for further words and phrases derived from Irish. In doing this, he tried to claim links between words like case as in case the joint and Irish casadh, gump and Irish colm and a host of other ludicrously improbable etymologies. He deliberately ignored any alternative derivations or anything that did not confirm his ridiculous hunches. For example, he claimed that swoon comes from Irish suan, meaning sleep. Sounds convincing, except that swoon has an impeccable genealogy in English going back to Anglo-Saxon, so the similarity with suan is pure coincidence.
However, if he had stuck to single words like this, his book would still have been a pamphlet, so he made up lots of ridiculous phrases like béal ónna, uath dubh, uath-anchor, gus óil, éamh call, árd-iachtach-tach, sách úr etc. etc. Hardly any of the phrases in Cassidy’s book are genuine Irish. The vast majority are the most imbecilic concoctions. As David L. Gold has pointed out, Cassidy’s contribution to the study of etymology was less than zero, because not only did he fail to produce any genuinely valid or potentially interesting derivations, he muddied the water by producing hundreds of entirely fake ‘Irish’ phrases which are still doing the rounds on the Internet.
If that weren’t enough, there are also huge questions to be answered about Cassidy’s academic record. When I started this blog in 2013, I still thought Cassidy had a university degree. This in itself would raise questions because you would normally expect a university lecturer to have at least a Master’s and often a doctorate. However, Cassidy’s sister Susan (no fan of her brother) told me that he had flunked his Cornell degree in 1965. This was confirmed by the Cornell registrar, Cassie Dembosky. In other words, there is not a shred of evidence that Cassidy had any qualifications at all, so it is hard to see how he managed to work for twelve years as a university lecturer. The only explanation, as far as I can see, is that he lied about his qualifications.
There are other strong indications of Cassidy’s dishonesty. He left reviews of his book on line using sockpuppet identities, which is not only highly unethical, the way it was done was incredibly incompetent. You would be in no doubt reading these fake reviews that Cassidy was the author.
Other details of his biography also raise questions. He was apparently working in the newsroom of the New York Times when JFK was shot. Except in reality, he didn’t work there until two years after Kennedy died.
Everything about this man is dodgy, suspect, hooky. His American and Irish cronies, lackeys and enablers can deny the truth as much as they want. It remains the truth. What is important to me is to get the message across that Cassidy knew nothing about Irish and that most of his claims are based on made-up expressions which clearly demonstrate Cassidy’s profound lack of respect for the Irish language and the people who speak it.
cassidyslangscam 
If Cassidy’s dictionary had any scholarly value (by which I mean, if it contained accurate etymologies overlooked by students of Irish influence on English), he should have had no trouble winning the approval of members of the departments of Irish, Celtic languages, and English in Ireland (South and North) and members of relevant research institutions there, such as The Royal Irish Academy.
All of them, however, ignored his dictionary. Their silence speaks volumes.
Now that Danielomastix has debunked Cassidy’s dictionary, believers in its scholarly value, instead of childishly attacking Danielomastix (childish, because attacking the messenger if you don’t like the message is childish), should turn to members of those departments and institutions for opinions. What say they about Cassidy’s dictionary? Surely his supporters can coax them to break their silence.
Very true, David! Unfortunately, some of Cassidy’s less gifted advocates seem to think that the silence of academia is either neutrality or even tacit support. In reality, of course, their silence does speak volumes and it says nothing good about Daniel Cassidy. In general, academics tend to ignore pseudo-scholarship on their patch rather than tackling it. Given the way that so many people get their information from sources like Twitter and Facebook these days, perhaps professional academics in the field of linguistics should be a bit more active in correcting this nonsense rather than just hoping it will go away by itself.