The reason could be that the cartoon creator wanted to add a funny or unique trait to the character. Or, it might be related to a particular plot point where the bad breath leads to some funny situations.
Maybe they ate something stinky or didn't brush their teeth.
Maybe she ate something smelly or has a dental problem.
The reason might be that she has a cold or sinus infection, which can cause bad breath. Or perhaps she's been drinking coffee or other beverages that leave a bad taste in her mouth.
Maybe they got caught in the rain or had a rough morning. Simple things like that can cause a bad hair day for a cartoon character.
It could be that the cartoon kid is in a situation where they need to hold their breath to hide or stay quiet. Like when they don't want to be noticed by someone.
The reason for the cartoon dog having bad teeth could be a combination of factors. It might not have access to proper dental care in its fictional world, or it could be a result of a genetic issue. Also, it could be a creative choice by the artist to make the dog stand out and add some charm or humor to the character.
The cartoon girl might have a bad face because the artist wanted to convey a certain emotion or create a particular storyline. It could also be a visual cue to show that she's facing some kind of challenge or difficulty.
Maybe the artist wanted to create a unique or funny look for the character.
Maybe it's a creative choice by the artist to give her a unique look.
Maybe she wasn't well-prepared or was too nervous during the interview.
They can be popular because they offer a lighthearted and humorous take on a not-so-pleasant topic, making people laugh and forget about the grossness for a moment.