To be sure, it is terribly upsetting when someone else castigates you, and it's worse when it's done publicly. But that doesn't necessarily mean you can win a lawsuit for defamation against them - at least not under New York law.
In fact, there are two (2) primary reasons why most defamation lawsuits fail.
(1) There's a fundamental distinction between false assertions of fact, and mere expressions of opinion. The former is potentially actionable; the latter is not.
To that end, New York's courts have summarized this principle as follows:
A claim for defamation must allege a "false statement, published without privilege or authorization to a third party, constituting fault as judged by, at a minimum a negligence standard, and, it must either cause special harm or constitute defamation per se." O'Neill v. New York University, 97 AD3d 199, 212 (1st Dept 2012) (quoting Salvatore v. Kumar, 45 AD3d 560, 563 [2nd Dept 2007], lv app den 10 NY3d 703 , quoting Dillon v. City of New York, 261 AD2d 34, 38 [1st Dept 1999]).
"Since falsity is a sine qua non of a libel claim and since only assertions of fact are capable of being proven false,a libel action cannot be maintained unless it is premised on published assertions of fact," rather than expressions of opinion. Brian v. Richardson, 87 NY2d 46, 51 (1995); accord Sandals Resorts International Ltd v. Google, Inc, 86 AD3d 32, 38 (1st Dept 2011).
(2) But there's another reason that many, if not most, defamation claims fail: lack of damages.
The 2009 Brooklyn trial court decision in Heredia v. Taylor illustrates this point rather nicely.
In that case, Heredia claimed that that Taylor had publicized nasty allegations about her. Interestingly, the Court did not dismiss the case because the plaintiff's claims were not credible; to the contrary, the Court explicitly noted that the defendant had all but admitted making those derogatory statements.
Rather, and despite the defendant's admission to making the nasty statements about the plaintiff, the Court dismissed the case because the plaintiff for the simple reason that she had not produced "one scintilla" of proof that she had sustained any damages as a direct result of the defendant's actions.
Why this Case Never Should Have Been Brought
I find this decision disturbing, because if accurate, the plaintiff's attorneys should never have taken the case.
What were they thinking?
Pretty much every case has two elements: liability and damages. Even under the best case scenario, such as where the defendant concedes liability, your case remains worthless if you have sustained no personal injuries or damages. For example, if the defendant runs a red light (or stop sign) as a pedestrian is proceeding through the crosswalk, and the defendant manages to avoid hitting or injuring the pedestrian, what do you think that pedestrian's damages are? That's right - zero; the pedestrian should be grateful.
The same analysis should hold true here.
If the plaintiff sustained no demonstrable or provable damages as a result of the defamation (which more often than not will be the case so long as it remains in the private, rather than small business or commercial context), the defendant could get up and admit making the statements, but it will not change the ultimate result of the case - that it is worthless.