For its Oct. 11 episodes of “New Girl” and “Brooklyn Nine-Nine,” FOX aired two back-to-back crossover episodes in which main characters from each show made appearances on the other.

The “New Girl” principle characters visited New York, and some of them encountered the detectives from Brooklyn’s 99th precinct in a few short, silly scenes. While the crossover had the potential to bring two well-loved sitcoms together, the scenes the shows shared were awkward and didn’t live up to either show’s historic hilarity.

Crossover episodes are not new, but they often take place in shows that were already previously connected in some way by the writers. Prior to the Oct. 11 episodes, fans of “Brooklyn Nine-Nine” and “New Girl” were given no confirmation that both FOX shows took place in the same fictional world.

Many crime shows in the same franchise have obvious opportunities to share characters and storylines, and they take advantage, such as the various “CSI” and “Law & Order” editions as well as the Chicago-centric P.D., Med, Fire and Justice. But, shows with characters already known to exist in the same universe are a lot different than forcing two shows to mesh.

“Law & Order: Special Victims Unit” and “Chicago P.D.” had several crossovers woven through episodes of both shows. Much like the FOX crossover, that crime-show mixing didn’t hit the mark. The need for the “SVU” “P.D.” crossovers was not only unclear by marred by stilted dialogue, references to unclear plot points and open-ended storylines. Someone unfamiliar with “P.D.,” would not understand the vague references to that show’s characters’ backgrounds, or “SVU”‘s.

Those kinds of crossovers are nothing more than marketing attempts to expand the viewership of the less popular show. When the episodes are forced, it’s obvious and affects the quality of the shows. But, not all crossovers are necessarily bad.

In July 2006, Disney aired the perfectly executed, three-part crossover “That’s So Suite Life of Hannah Montana,” which mixed “That’s so Raven,” “The Suite Life of Zack and Cody” and “Hannah Montana.” That crossover didn’t rely too heavily on prior knowledge of the different shows, didn’t force unnecessary plot points and just amplified the quality of the original shows. A few years later, Disney aired another crossover with two of the three shows in the previous one as well as the newer “Wizards of Waverly Place” titled “Wizards on Deck with Hannah Montana.” Much like the other, this crossover lived up to fans’ expectations.

The CW’s “The Originals” started in 2013 as a spin-off from the network’s popular show “The Vampire Diaries” and have both shared characters and hosted well-thought-out crossovers since the spin-off’s premiere.

Those Disney and CW episodes didn’t try too hard to get audience members to go and watch any show they didn’t previously with vague references to past events and plots. FOX and NBC could take some pointers from those networks with future crossovers, though it would be better if they didn’t try anymore.