Just because you might dress up dissing your competition as a mildly dirty joke --even a fart joke-- does not necessarily mean that you can expect to come away from Court smelling like a proverbial rose.

That could be said to be the bottom (groan) line of an entertaining law blog article about false disparagement and the failure of a "puffery" defense.

Penned by legal bloggers Amy Ralph Mudge and Randall M. Shaheen, representing Baker & Hostetler LLP,
they really cut loose with the puns and wit, while making serious and useful points about dirty competitive strategies.
Lexology version:

Original:
https://www.adttorneyslawblog.com/advertising/butt-isnt-it-just-puffery-if-it-is-funny/#page=1

In case you wish to know, "Puffery" is the legal argument that the offensive suggestion is too ridiculous --or hilarious-- to be taken seriously by a reasonable person.
https://definitions.uslegal.com/p/puffery/

There are object lessons for writers who do their own marketing. Not every author compares his/her/their work to a rival's works in ways that compliment the rival.

Does anyone still read Charles Kingsley's The Water Babies? This writer has never forgotten the lessons of Mrs. Do-As-You-Would-Be-Done-By  and Mrs. Be-Done-By-As-You-Did. 

Another recent legal blog deals with truthful advertisements, from which one can extrapolate advice about comparing your products and services to those of others... or not.  Christian P. Foote, writing for Carr McClellan

Original:
http://www.carr-mcclellan.com/insights/truthful-ad-claims-product-not-implied-false-comparisons-competing-comparable-products/

Lexology:

One would have to have a major inferiority complex to sue a rival for claiming that their (the rival's) own sweet product has "no added (ingredient)" which must mean the same thing as the rival disparaging the offended party's product by suggesting it is unnatural.

Alas, some will see offensive "micro-aggression" where none was intended. The internet is full of potential for such misunderstandings.

On a positive note, the FTC (Federal Trade Commission) is open to public comments on its Endorsement Guides. The guides mostly affect Influencers, but commenting is an opportunity for writers to comment publicly with wit and charm.  Your name and comment will be published.

https://www.ftc.gov/news-events/press-releases/2020/02/ftc-seeks-public-comment-its-endorsement-guides?utm_source=govdelivery

All the best,

Rowena Cherry