Bob is actually trying to start a war or at least a scandal
Bob's government is sending threats and he is not supposed to be polite.
Bob is the first Ambassador ever sent to a newly discovered country. His intel botched the job and he doesn't know what is considered rude here.
Bob remains on his absolute best behavior while at the imperial palace of Cloud Cuckooland.
Bob even delivers declarations of war politely. After all, a massive apocalypse is no excuse for rudeness, is it?
Bob is a polite Ambadassador who defends Cloud Cuckooland's king against potential assassins and rebels. After all, shouldn't he work for the nation he interacts with and not turn a blind eye to its woes?
Bob burps at the dinner table, but quickly excuses himself.
In Cloudcuckooland, insulting authority figures is seen as a test of skill, flirting with a married woman is a custom to compliment them, and putting your elbows on the table a sign of respect to the chef. It seems Bob has done his homework, and only made to look otherwise.
Only to learn that "excuse me" is not the proper response to a burp in Cloud Cuckooland.
But his behavior is still very rude and ignorant, and still reflects poorly on Tropestan.
But these customs are not done among the nobility, thus being seen as an insult to the Emperor and Empress.
Parodied: Tropestan and Cloud Cuckooland are enemy nations, so Bob's rude behavior makes him a hero back home.
Zig Zagged: Once the Tropestani government hear of Bob's boorishness abroad, they send in Alice, an Ambadassador who can defuse the situation. Bob stays around, but only as a gag.
Averted: Bob does not visit Cloud Cuckooland, or interact with any political leaders from there.
Exploited: The emperor of Cloud Cuckooland had been looking for a reason to declare war on Tropestan before Bob came along, and used Bob's actions as a pretense for war.
Defied: Bob (even despite being very drunk) remembers he's supposed to be impressing the emperor, and so does his best to remain on his best behavior. He also took the time to study up on etiquette in Cloud Cuckooland.
Discussed: "Remember what happened last time Bob went to another country? Is it really a good idea to send him to Cloud Cuckooland?"
Conversed: "Considering that an ambassador's job is to promote peace, you'd think they'd do a better job of not pissing others off."
Implied: Bob isn't allowed in Cloud Cuckooland. He won't say why, but it's easy enough to guess.
Deconstructed: Obviously, not the best thing for foreign relations, or preventing Cultural Cringe.
Reconstructed: Bob publicly (and without making lame excuses) apologizes for his bad behavior. The emperor of Cloud Cuckooland accepts the apology, and they start over.
Played For Laughs: Bob gets booted out of the country by the emperor. Literally.