Disparagement isn't what it used to be.  In the good old days, disparagement meant a marriage to a social inferior.  The word itself is derived from the Old French word, desparagier, meaning to degrade.  The French, of course, borrowed the word from the Latin prefix dis, meaning away from, and pars, meaning equal.  The English word "peer" is derived from the same Latin word par.  A peer is one's equal.  In sixteenth century England, the barons took umbrage at being forced to marry beneath their station.  Thus, they forced King John to agree that he would no longer compel such unions.  The royal promise, which wasn't limited to the nobility, was memorialized in the original (1215) version of the Magna Carta:

Heredes maritentur absque disparagatione, ita [tamen] quod, antequam contrahatur matrimonium, ostendatur propinquis de consanguinitate ipsius heredis (Heirs are entitled to be free from disparagement, thus before a marriage is made, it shall be made known to the nearest blood relative of the heir.)

Disparagement is no longer limited to matters matrimonial.  In today's parlance, just about anything can be disparaged (i.e., degraded).  Social media and the internet have made it possible for people to widely publicize their opinions of businesses, their products and services.  Some companies, borrowing (albeit unconsciously) from the Magna Carta, have tried to put the kibosh on disparaging reviews.  Paul Alan Levy, a member of Public Citizen's litigation group, recently wrote about one Texas company's effort to collect millions of dollars in damages for a negative Yelp review in violation of an anti-disparagement clause included in the business' customer contracts.  See also UCLA Law School Professor Eugene Volokh's post on the same subject in The Volokh Conspiracy.

Here in California, a plaintiff in this type of action would run into Section 1670.8(a) of the Civil Code.  However, that statute is less than pellucid, as I noted in this 2014 post.