But the cat came back. It just couldn't stay away.

Stayaway Motion Activated Cat Repellent | Pest Repeller Center
Motion-activated air sprayers. We like these the best because: 1. They do not damage the cat or its psyche. 2. There are virtually no cats that are resistant to air spraying hiss. Two popular models are and StayAway, which both work similarly, but StayAway air is accompanied with a beep, which means that even when the air canister is empty, the cat will still run away because it will know what’s coming next. UPDATE: Unfortunately StayAway has been discontinued. You can . The drawbacks of air sprayer deterrents are that they cost money, use compressed air canisters that last for only a few hundred sprays (refills are available), and you need to turn them off when you are in the area.
Frightening cats with sudden bursts of water, and conditioning them to stay away from virtually any area, such as:
Shake-Away claims to be the "strongest cat deterrent in nature," and I have to agree, judging by the ingredients. Shake-Away is a granular substance with the odor of fox and coyote urine. Even are smart enough to stay away from areas previously marked by much larger predators. One 20 ounce bottle will cover as much as 600 linear feet. Shake-Away is non-toxic to humans, animals, and flora. Like the "real thing," applications should be repeated over time or after stay away, Stay Away, STAY AWAY, cat stay away, Cat ..Stay away cat design T-Shirt | SpreadshirtThis Stay away cat design T-Shirt is printed on a T-Shirt and designed by
Once your cat has defined its territory,that's where it will tend to stay. It's there —it has its favorite resting and sleeping placesand it knows when and where you'll feed it. Unneutered males will roam those neutral territories,but females and neutered males almost never will —at least by choice. However, the cat can be frightened out of its territory —by another animal chasing it,by startling activity between itand its normal hiding places, etc. When that happens,it will run away from the threatuntil it finds a new hiding placewhere it feels safe —its fear of the immediate threat overridingits fear of (or respect for)other cats' territories.The StayAway automatic pet deterrent protects your porch, patio, potted plants, and countertops. Just place it in the area you want to protect, and the StayAway does the rest. When a cat approaches the area, the StayAway responds with a warning sound and a brief spray of "compressed air" to warn your pet away. Once your cat learns to recognize the warning sound, you can switch to the "sound only" mode to conserve compressed air for an even more economical solution.Wherever it found to hide,you can be quite certain it will stay thereuntil nightfall. Its fear is greater than the outdoor cat'sbecause the experience is totally new to it. After dark it may start cautiously exploringits immediate surrounds —just as the outdoor cat didwhen it first ventured outside. But it has no sense of "home" —all of its markings are in the house, not outside. Its instincts are telling itonly to find a hiding place —but that new hiding place is as likely to be farther away from homeas it is to be nearer. The indoor-only cat eventually return on its own —traces of your scent are outside, if not the cat's —but it's less certainthan it was for the outdoor cat.Thousands of my clients have tested and approved the Stay Away can! Mine has lasted for 3 years and still going strong! This is a very humane product giving a warning beep before the gust of air is expelled. Eventually you can turn off the air and the warning beep will deter your cat. We are proud to stock the brilliant Contech StayAway Motion-Activated Pet Deterrent!For the first few days, use the combined sound/spray mode. When the motion detector detects a cat's movement, it will first respond with a sound, followed by the spray of air. After a few encounters with the StayAway, most cats will decide that the sound is enough to warn them from off-limit areas.The reason this product works so well is that it trains cats to stay away from forbidden places at ALL times...even when you are out of the room, asleep or not at home! Other deterrents depend on your presence and your ability to swiftly respond and match "penalty" with the crime...cats soon come to realize that as soon as you can't see or hear their mischief, it's party time! But StayAway works 24/7...whether you're there to catch 'em in the act or not! Cats otherwise used to doing as they please the second you leave the place or shut your eyes soon learn...the punishment comes whether or not you're there! Eventually they become too scared to even go near that part of the room...at any time. It's an effective form of training that does pets no harm.