My friends' son wanted a cat - very badly. His parents, especially his mother, did not want him to have the said cat - also pretty badly. And not because they are not cat people - but because they knew that, despite his solemn wows to take care of his feline, very soon it would be mother's responsibility.
So, they enlisted my help in trying to explain to the precocious teenager all the negatives of being a cat person. He, however, was adamant; he will feed and water him or her, scoop the litter box, schlep him to the vet, give him medicine - the dude prepared himself for any and all eventuality.
Finally, I asked him the last question - how does he feel about cleaning kitty's puke? The poor boy was stymied - puke?!! What puke? What do you mean? Well, I explained, they get hairballs (and even meds don't always help) - and they puke.
And that, ladies and gentlemen, what stopped the enthusiastic young man in his desire to have a feline companion.