Ask them questions about indoor/outdoor, spay-neuter-declaw, and discipline techniques and make sure their answers make you comfortable. Make sure they have a regular vet (assuming this is not their first adoption) and don't be afraid to call that vet for a reference if you desire. Ask questions about any former pets who have died (can possibley pinpoint neglect and/or abuse). Ask why they want a pet ("my kid wants one", for instance, may raise a red flag). Make sure the main caregiver has come along, too (avoids "surprise" gifts to someone who may not have even expected or wanted a pet).

You may also want to get a reference from the landlord if the person rents, or from the association if they live in a condo, to make sure the kitty is not going to land at the pound when they get caught in a no-pets residence.

As far as specific personality traits, I have always found that the person who declares they can't decide amongst several choices is often a good candidate, as is someone who is clearly a warm, chatty person, even if that warmth is only directed towards the kitties.

Plusses are the candidate asking about current diet, types of toys he likes and bedding the kitty is using, or mentioning introduction techniques if there is already a pet in the home. Plusses are also the people who promise to bring the cat back to you and only you if the adoption does not work out for some reason, even if it's in the distant future.

Other red flags are unruly kids tagging along, or rough handling of the kitties by any person in the candidate's party. Don't be afraid to require anyone with young children who have not come along to visit again with the children so you can see how they will interact with the pet. A red flag is a person who wants several cats without mentioning preferred colors, sexes, or ages.

Some people and groups even bring the kitties to the adopter's home instead of having the adopter come to the kitties' hime so they can scope out the environment and get a better idea of how the kitty will adapt.

This would be regardless of whether the candidate was male, female, rich, poor, single, married, young, old, etc. There would be additional pointers if you had dogs/puppies up for adoption, but I am not an expert at that and you didn't ask about that!

These are some of the things that I can think of off the top of my head, but there are several other people, Aly for one, who have fostered and/or worked for shelters or rescue groups who can also offer their expertise.

Good luck with those little guys!