I totally get what you're saying, but it was super obvious! One of my relatives does that, leaves a tip on top of old receipts, papers and food - it just looks like pocket change! I pre-cleaned the desk and made sure there was nothing on it except for a crisp $5 bill, laying flat, face side up, lined up OCD style parallel to the edge of the desk. The only thing it lacked was a note screaming "please take me!" It's the same way I've left the tip when staying non CL, and it was always gone when we got back. This was our first CL experience, so we also thought that maybe it wasn't obvious that it was a tip! We tried 3 times in a row and every time, we came back to the room, the room was cleaned and there was the $5! And we had 2 rooms and it happened in both rooms. And we even left it there hoping the time they came by later for turndown service they would take it, but there it sat still on the top of the desk! We asked and they said they were not allowed to take cash tips. So next time I'm bringing treats for housekeeping too!