You just noticed your current cat’s expiration date expired a year ago.
Your current cat’s breath smells like Funyuns.
Frankly, your current cat’s a little too much of a bible thumper for your liking.
Your current cat loads dirty dishes in with the clean dishes and then runs them all through again.
Your current cat leaves big strips of tall grass whenever it mows the lawn.
Your current cat’s a gloater
Your current cat thinks Mt. Rushmore is a natural formation.
No matter how many times you try to explain it, your current cat keeps sewing the elastic waistband into the bottom of the pant leg.
You suspect your current cat is the one who maxed out your credit cards on http://www.bevmo.com
And finally, the best way to tell if you need a new cat:
You installed a nanny cam and, sure enough, it’s your current cat that keeps stealing the last maple bar.