Luna and Bugsy Nose Kissing Moment

It's very common for a cat to kiss each other nose. I really love when they do that, though I still don't know why cat love to kissing each other nose when they meet.
My sister have a theory about it, she said Cat kissing each other nose to find out if the other cat have wet nose or dry nose. dry nose mean cat is in good condition, and wet nose mean cat is not in good condition, such as hungry.
I don't know if my sister theory is right or wrong, but I think its very sweet