There are so many methods of encoding information into a printed picture, so relying on the absence of yellow dots is naive.
Seemingly random pixel positions shift, brightness shift, density shift, etc.
Seemingly random pixel positions shift, brightness shift, density shift, etc.
These are all hypothetical though. We don't know if these techniques exist in the wild.
Edit: If you want to check your printer then: print something to a piece of really white paper, scan it, and then use a diff tool like in Gimp after resizing it to easily spot the differences. If you are using off white paper you can scan it also before you print on it, and attempt to remove the paper's natural color variations before "diff"ing it with the digital version.