You cannot be spotted for any duration; the achievement fails even if you do not receive a bill for Disrupting Recordings or Harrassment.
The achievement is awarded at the bottom of the red carpet, before reaching DJ Grooves.
For newer players, this achievement will most likely not be earned in the first try. Given the new gimmick of stealth added in Dead Bird Studio, some players may not even know that one is supposed to avoid detection altogether. Re-playing the level with the intent to get this achievement will most likely grant it if the player has enough reflexes and can make quick choices.
A key component to the achievement is that the player must be completely undetected by the Moon Penguins and Express Owls. This means that the player must be not apprehended by any of the birds as well as not sighted and billed for Penguin/Owl Harassment. As such, the achievement requires a lot of observation, awareness of the player's situation, and most importantly patience.
Given how most of the early examples to how the detection gimmick works are easy to manage and able to be breezed passed by players aware of their limitations, the challenge can be diminished to a trivial difficulty for a majority of the stage. That said, some areas may have unclear or unfair collision detection, so multiple attempts may still be needed.
One area of notice is a single segment near the end of the level where Hat Kid needs to ride on an automated train past a Moon Penguin and Owl that periodically overlook the path of the player. Since the movement of the train is automated, this can lead to a really difficult segment, as the terrain is limited enough for the player to have very little time and room to avoid detection, failing the achievement and requiring for them to be returned to the Hat Kid's Spaceship for a retrial. Bizarrely, using the Ice Hat renders Hat Kid invisible during this section, letting the player simply ride past.
The Time Stop Hat with the Mad Hatter Badge will give you much more reaction time, making this achievement much easier to earn in a majority of the segments.