Shortly after he adopted an unwanted boa constrictor, Hal Herzog, a psychology professor at Western Carolina University, was accused by a colleague of feeding it stray kittens.
He wasn't. But the accusation, he wrote last year, "forced me to confront questions ... about the moral burdens of bringing animals into our lives".
America's 94 million pet cats, he calculated, each ate about 50 pounds (22kg) of meat a year, while snakes ate only five. Therefore, he concluded in Some We Love, Some We Hate, Some We Eat: Why It's So Hard to Think Straight About Animals, "the moral burden of enjoying the company of a cat is 10 times higher than that of living with a pet snake".
So what about the moral burden of enjoying the company of a giant panda? Endangered at home, pandas have nevertheless served as ambassadorial gifts from China for decades. Between 1958 and 1982, more than 20 were given away to nine countries. In 1972 Ling-Ling and Hsing-Hsing were a big hit in Washington's National Zoo and were credited with balancing East-West relations.
Now Kerching-Kerching - sorry, Tian Tian and her partner Yang Guang, settling in to their new life in Scotland - are expected to balance the books at the 100-year-old Edinburgh Zoo, which this time last year was facing the prospect of "a series of cuts after a drop in visitor numbers".
Perhaps as a result of China's bearhug embrace of capitalism, the days of the furry freebie are over and Scotland has had to rent its bears. Edinburgh's Royal Zoological Society, which desperately hopes the couple will prove to be a breeding pair (wishful thinking represented by the hundreds of toy baby pandas already resident in the zoo's shop), will pay £600,000 (Dh3.5m) a year for the next decade.
What's in it for China, which most surely does not need the rent? Who knows. Perhaps the pair are Trojan Pandas, designed to distract decadent western minds from the coming sack of the capitalist Troy by the ascendant eastern economy.
But even less clear is what's in it for the pandas.
Of course, the arrival of the star attractions was dressed up by the zoo in the emperor's clothes of education and conservation. The zoo was "supporting giant panda conservation and ... enhancing our programmes in education, science and conservation".
Sure, said The Born Free Foundation. Tian Tian and Yang Guang were nothing more than "commodities in a primarily commercial exchange ... this has less to do with conservation or education, and much more to do with resurrecting the fortunes of a fading visitor attraction".
Does it matter what the zoo's motives are, provided the animals are well looked after? Heck, they are being treated like stars, with organic bamboo specially flown in from home!
Well, that depends on your moral burden. All zoos, as a 2001 paper published in the journal Tourist Studies pointed out, are founded on "the theme of power". No matter how nicely designed they are, how cute the fluffy toys in the shops are, it remains a fact that "almost total control is exercised by humans over the animal's movements and activities".
We delight in projecting human characteristics onto animals when it suits us - witness Mickey Mouse, Fantastic Mr Fox, Ratatouille, The Lion King and Kung Fu Panda, et al - but we conveniently withdraw such anthropomorphic generosity whenever it suits us. Think experiments on white mice, fox hunting, rat poisoning, big-game bagging and, well, Edinburgh Zoo.
At best, this is conscious hypocrisy; at worst, some kind of mass split-personality disorder.
And if pandas really knew kung fu, it's a hundred bucks to a kilo of organic bamboo that some keeper in Edinburgh Zoo would be in for a hell of a kicking.