…to the cook, and not a sign of rudeness.
I heard that in some countries that burping after meals is actually polite. It means that you liked what was served. Then again, I also heard that this is a complete myth, and that burping is rude everywhere.
Can someone confirm this?
I first heard about it in the movie Ben-Hur, where one American actor told another American actor, by gestures, of the custom. I don’t know if it was in Lew Wallace’s book, or whether Wallace ever left the US.
Like you, I don’t know if it’s true. 
I’ve heard it said about some middle eastern cultures. If it’s true, I assume the “my compliments to the host” burp is audible but fairly soft.
Many of us can chug a Coke, wait three minutes, and release a belch that damages the neighbor’s chimney. I doubt that any dinner host would be flattered, regardless of culture. Flattened, maybe.
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It is true in China. I don’t mean an obnoxious beer bong bull roarer belch for the olympic gold. Although, to be fair, I have heard demunitive grandmothers contend for the crown. A nice belch is considered a normal body function and not something to be ashamed of. And during or after a meal is generally considered a complement to the chef.
It’s not considered rude at all in Kenya. Same with unadulterated nose-picking. What is never done, or at least never heard is farting. Not even amongst children.
In my region of Spain the children are taught that burping is extremely bad manners. When a child burps, (not on purpose) all the other children look at him as if he has committed the crime of the century and parents will yell at their children for even involuntary burps.
I don’t know if this is concrete enough for this forum, but when I was a kid I read a book about a Zulu girl, and burping was the mandatory way her father told her mother he’d enjoyed the meal. It was fiction, but it was the kind of book that’s all about giving you the details of Zulu culture, so I lean towards thinking there was some basis in fact.
My dad used to say that farting was considered.a complement to the chef in Japan. True, or just an excuse for a loud fart?
What I know about Japan is that it is good to audibly slurp noodles. I once went to a Kabuki theater, sitting in the nosebleed section and when the actor slurped his noodles, you could hear it in the rafters. Of course, he was exaggerating as a good actor will. But don’t ever, ever, blow your nose in public.
I was told this in Singapore.