If you already have a job but find yourself looking for a new one, the dead give away in the office is that you suddenly come to work dressed up after already establishing yourself as a dressed down kind of person. That usually leads to complications. I’ve seen people get let go because the manager felt that the person was interviewing elsewhere and thus wasn’t a team player. Brutal.
What I suggest is randomly wear a suit to work to throw people off. Just get dressed to the nines, go to work and do what you usually do. Changing it up like that, especially if you’re a “dress down” type of employee, provides great cover for those times when you’re searching for a new gig but don’t necessarily want to lose the one you have at the moment. This is especially useful for those times when you have a interview during the workday.
Of course if you’re a ditch digger, I’m clearly not talking to you (hahaha) but I’m going to assume that you are already know that.