I've heard that before. People complaining that "My adoption center asked so many questions that it's easier for me to go to a breeder and just buy a dog."
Well, this kind of situation is why rescuers slowly make their adoption processes longer and longer, and stricter and stricter.
I originally started out with a fairly brief adoption contract. It's still short, compared to most groups. But I require an indoor home (because my cats are shy and I also rescue wildlife and find putting tame cats outdoors a violation of both my missions to keep cats and wildlife safe). I used to leave declawing out of the contract (although I discouraged it in the interview), because I felt people with lupus, AIDS, etc. should have the option of declawing. I now ban it in the contract because I've had cats returned for behavioral reasons because they were declawed. If someone wants a declawed cat, I'll now go look for one for them for them.
I used to send out my smallest kittens unfixed, with a free spay/neuter certificate, and follow up by phone, until a cat was returned to me this summer as a full-grown spraying tom. Obviously my follow-up was not good enough. Now, unless the cat is adopted right in my neighborhood, they all must be fixed, no matter how young.
So slowly my adopter process becomes stricter and stricter, while people can pick up a free kitten from a box at the Farmer's Market with nary a question.
Getting a cat back really puts a wrench in the works. Now, instead of a cute kitten, I have an adult cat to place. A FRIENDLY adult cat who needs petting and combing and reassurance (unlike my feral adults, who like human contact, but require less of it). There is nothing sadder than a friendly adult cat stuck in a shelter or cat facility. Even a good one.
I think a balance needs to be struck in adoption. When I sit down with people are start the interview, I let them know right off that my questions are not a reflection on them. They are a reflection on past failed adoptions. This seems to help a bit. And when someone just isn't worth the risk, I try to be gentle with the refusal. "I think you would be happier with a kitten with less baggage," or "I think you will have a more successful relationship with a cat if you wait until you are settled in your next apartment." I let people know they should consider their first two weeks "fostering," so if the cat doesn't work out, they don't need to feel bad sending him back.
I'm still not as good about following up as I should be. Email has been a huge help.