I said "sometimes", though the rest doesn't really apply. I don't only do this for other TCS members or cat lovers. I do it kind of randomly.
When it IS a fellow cat lover, like hubby or my parents who know the pets are their grandbabies, not only do I sign their names, I make the pets sign it!
I don't only do this with the kitty, I do it with them all. And we all know animals wouldn't normally mark something with a paw print, so, here's way more than you needed to prove I was crazy- I make them mark it a more natural way! The dogs I make lick it.
I know! Just a little spot, can't really see it.
Or if that doesn't work, I do with them what I do with Evie- I make them bite it! Then the chins I have chew a bit off the edges.