Usually you'll encounter one scurrying down the hall, avoiding your footfalls! Like that's not enough 'evidence'...haha!
But if there isn't one to 'lead the way' into our meager apartment, you will soon find cat toys galore (what ones they haven't lost for the day), cat scratch toys, a kitty tree complete with hanging mice and their food and water dishes, more cat scratch posts, and a kitty condo. And of course, eventually the feline greeting committee will soon show it's face, usually beginning with Ms. Brazil, the pest! Lol!