Or if you smack yourself on the forehead when you’re halfway to wherever you’re going, figure there’s no chance it’s still there, and then eventually come back and are surprised to see that it remains.
I am a diverse pet owner 
Or as you leave a room to grab a napkin you glance around and say “Don’t EVEN think about it!”, you might be a pet owner.
Oh and “watch my plate” is not a strange comment for anyone in the house to say then you might be a pet owner.
My aunt used to do that with her chihuahua. It was horrible. And we had a beagle the time, so we were used to witnessing disgusting canine activities.
If you notice someone has many, many microfine punctures in their hands, the odds are good they have a new kitten.
If you encounter someone walking a dog and pushing a baby in a stroller and you say “Oh, what a cute baby!” instead of “Puppy!” you are not a pet owner.
“Unanticipated nighttime diarrhea and vomiting have also been known to happen,” she observed from all-too-recent experience.
If you gather up and put away all the toys BEFORE small children come to visit, you may be a dog owner.
If someone’s never seen more than three links of the food chain at work, they’re not a pet owner.
I see a lot of fur comments about dogs. Not all dogs shed to excess.
I am a dog owner but I don’t do “fur”. I have a Poodle and an Affen for that very reason. Their shedding is next to none.
Anyway, my contribution:
If you hear noises in the other room while you are in bed and worry that someone broke into your house, you are not a pet owner.
My dog sits under our chairs very determinedly at dinner, in the utterly vain hope she will catch something from the table. She gets a nudge from the foot, a command, and/or a sharp clap.
Also, if you don’t know how to do the leash dance, you’re not a dog owner.
If you pause by the mirror for a “shoulder check” before going out, you’re a bird person. :>
If you know the names of the dog neighbors, but you’re not sure about the names of their human family members, you’re a dog person.
Sailboat
If you don’t know what lolcatz are, chances are you aren’t a pet owner.
If someone mentions a kitten/puppy and you don’t ask for pictures, chances are you’re not a pet owner.
So every non-pet owner is afraid of dogs? :dubious: I may leave unfamiliar dogs alone, but I sure as heck don’t act as though every approaching dog is about to maul me.
Unless it’s a particularly ugly dog.
I once had to remove a pet boa constrictor from my bra, but I can’t figure out how to work that into the theme – after all, how many snake owners are women? “If you’ve never removed a snake from your bra, you’ve never been a snake owner” just wouldn’t apply to (most) men.
Concerning the non-owner scared of dogs thing – I work at an aunt’s grooming shop (mostly dogs, the occasional long-haired kitty needing mat removal) and a customer the other day commented that when I came in, she knew I worked there because I didn’t act scared when I walked in and her largish yellow lab headed straight for me for attention. Granted, I’m very small, but I can’t imagine when I’d ever be afraid of an obviously friendly lab. They’re about my favorite dogs! But I didn’t argue with her, since she’s helping to pay my salary in a very direct way. Instead, I fussed over her lovely dog. I don’t have a dog right now, either, though I could very easily have acquired a puppy last week if it weren’t for all the good reasons I shouldn’t have one right now. sigh
Oh, man, I gotta disagree with this one. It’s like pumping other people’s kids full of junk food–hey, it’s fun to spoil them and it’s not your dog learning rotten manners, right? 
I can’t tell you the number of times I’ve had to stop random people encouraging him to jump up on them. “It’s okay! I have a big dog at home!” No, it’s not okay. Thank you for petting him, but he weighs well over a hundred pounds. We don’t want him to accidentally hurt someone, so we insist he have good manners and sit quietly.
If someone asks you if you have any pets, and you start naming them by species… you might be a reptile owner! (0.2.0 Elaphe guttata guttata, 1.0.0 Morelia spilota cheynei)
If you walk into the living room and see the dog leashed to the guinnea pig, and both of them staring pitifully up at you, and it doesn’t faze you, you don’t own a 5 yo girl (and a dog and a guinnea pig).
I often find myself using the words “disgusting” and “beagle” in the same sentence.
Yet another sign of a pet owner.
YMMV depending on the color of the dog’s fur and your clothes. I have a black Labrador. His fur is jet black and would be hard to notice against black clothing. My other dog is pure white, so white would be a good color choice for clothing.
We have springer spaniels. We’re screwed!!
Which reminds me of a corollary: If you’ve had to give up wool coats, you’re probably a (long-haired) dog owner.
Or he may be a deep sleeper, like my uncle. With a yappy dog, plus hens and cats all over the yard (he lives in an old farmhouse), you’d think there wouldn’t be a need to:
- set up the TOA in advance,
- ring the bell,
- slam the door,
- honk the car’s horn,
- and finally call him on your cellphone, by which point the yappy dog is about to have a heart attack and we have half a dozen cats staring at us from the wall.
It was equally bad when there were three dogs and a horse, but back then my aunt hadn’t separated from him yet; she would usually hear the ruckus and come open.