The day after your meeting, send the applicant a really nice email, thanking them for taking the time to come and meet you and your pet. Be as honest as is safe and comfortable about the reason you’ve decided this isn’t a perfect match for your pet. Hopefully they’ll be just as gracious as you.
If you don’t feel comfortable giving a reason, don’t! Here’s a sample of an email you might send:
Thank you so much for taking the time to meet with us! I think you’ll make a wonderful home for a lucky pet, but I hope you’ll agree that your home isn’t the best match for Fluffy. I wish you the best of luck in your search for a new family member. Thank you again!
If you want to go the extra mile, you might even send them a link to a similar pet for adoption on Miwuki!