Regarding clothing:
Many fiscally responsible people are just not interested in clothing. At all. No interest. Therefore, such folks cover themselves with clothing mainly to be minimally socially acceptable and not noticed when leaving their house, as showing up naked or in a bathrobe and shower shoes would lead to job loss and possibly arrest. I have worked with many engineers like this.
Such folks generally do not care to have their appearance or apparel commented upon. And if one doesn't care about clothing, wearing what is least likely to be noticed depends upon where you live. Where I live, at work/the airport/on the street the "pay no attention to me" uniform for men is khaki pants and a neutral colored polo or button down shirt. Exactly like the patio party photo. I have a colleague who has never had a car or even a driver's license, saves all his money, and cooks for his hobby, but he could pull up a chair at that party and no one would notice him. Where my brother lives, the "pay no attention to me" uniform is jeans and a plain, dark colored t-shirt or flannel shirt. The khakis would get you noticed, so I bet my colleague would change into his jeans and a t-shirt. Just because he doesn't want people to think about what he is wearing . . . ever.
When in Rome, as they say, blend. That doesn't mean you have to take out a car note, of course.