The Good; pick the best gerbils, train up that Macaw to talk serious smack or repeat John Tittor-isms (the best kind of Macaw!).
The Bad; Getting too attached to one of the sentient animals only to have it sold to somebody else. A small heartbreak for both you and the animal involved.
The Ugly; hopefully you won't be witness to a pervert's demented desires to poison all open-penned animals, causing them to die or become so sick that they have to be put down.
Walking into a pet store to get fish food and seeing all the owners/employees cry about the event was just... some people are just sick like that I guess.