Obviously, anyone who is inclined to abuse an animal is not ideal pet owner material. I wasn't referring to THOSE sorts of people, who should probably not even be allowed to have a houseplant of their own, but to people who have good intentions, but still cannot provide the home that an animal needs to thrive.
1. Time. I think that this is the big one. If someone does not have time to add anything else to his or her schedule, then introducing a new animal to his household is probably a big mistake. Is there a work-around? Sure. If an adopter can afford it, he could hire someone to look in on the animals in the middle of the day, or even take the new pet to daycare. Or someone with less money might be able to have a relative or neighbor check in with the animals. Maybe with cats, who use litter pans indoors and don't necessarily need outdoor bathroom breaks, someone could choose to adopt two, to keep each other company during working hours. But in my humble opinion (and take that for whatever it's worth) if someone has to work long hours, and has a busy evening social schedule, or will have to leave the pets alone to travel a lot, that person should think long and hard before adopting an animal.
2. Stability. I will admit it. I torture myself on a regular basis, and read through the ads on Petfinder, or at the local rescues, reading the descriptions of the animals that are looking for homes. But one side-effect to this rather masochistic hobby of mine is that I read lots and lots of reasons that are given for surrendering an animal to a shelter. And one of the big ones is that the owners had to move to a place that did not allow pets. Now, I know full well that we can't see into the future and plan for every eventuality, and I know that the economy is still pretty rotten, and a lot of homeowners are being forced to "downsize," sell their homes, and move into rental properties, some of which do not allow animals. So I'm sure a lot of these surrenders are due to that. But some of them make it pretty obvious that the person KNEW that their housing situation wasn't permanent and chose to bring an animal into it anyway. That is selfish. Animals are not throw-aways, to be discarded whenever they cease to be convenient. If a person doesn't believe that they can provide a home for that animal for the forseeable future, then he or she has NO business getting one. And for heaven's sake, if a person does have to give up animals for housing reasons, every reasonable effort should be made to rehome these pets, instead of surrendering them to a shelter.
3. Babies. Everyone loves babies. But oftentimes, pets don't. It seems like a lot of Petfinder ads mention a new human addition to the household being the reason that a pet is surrendered. I find that very sad, and brings me back around to my "animals are not disposable" argument. I know that many, many households manage to get through those rocky first few months with both baby and animal, so I'm not saying that someone should never ever combine babies and pets. But I do think that if a person is going to be having a little one any time really soon, they should be extremely cautious about getting a new animal. Babies take a lot of time, and let's face it, those first few months of sleep deprivation, hormone fluctuation, feeding schedules, and sometimes inexplicable screaming are going to be challenging, and maybe even a little demoralizing. It might be good to plan ahead - if a new mother (or father) is going to be tied up with taking care of baby's needs, who is going to walk the dog? Clean the litter boxes? Give the animals affection and attention? If the answer is "no one" then maybe it would be best to wait until the baby is a little older.
4. Money. Let's face it, few of us (including me) are rich, with limitless resources. And again, we can't see into the future and know how much money we're going to be asked to spend to keep our animals healthy. No one can predict chronic illnesses, lay-offs, etc. But some people clearly can't afford to keep an animal - if someone is struggling to feed themselves, then they have no business getting an animal. That animal is just going to be eating sub-standard food (or possibly not getting enough food,) skipping routine vet care and vaccinations, and not getting taken to the vet in emergency situations due to lack of finances. I will totally sympathize with an owner who is either in reduced circumstances or dealing with some major health expenses, but get really aggravated when I hear people talk about not wanting to spend the money for vet care, high quality (or at least decent quality) food, or even heartworm preventative. These things shouldn't be optional, and anyone who thinks that they are, shouldn't have a pet.
So... those are the reasons to NOT get a pet that jump out at me. Am I forgetting anything?