When you make short films with not always a complete crew, you learn exactly what all those jobs are for. On my first professional short, we didn't have an A.D. So as a director I had to stress about moving the crew along.
On my latest crew, we had a great AD and a terrific camera crew. We decided to skip having a costume designer, because the actors were just wearing their own clothes. So, we learned what costume designers do. Costume designers make sure that you do not put a black jacket on a girl with black hair. Costume designers also make sure that the pink blouse an actor is wearing does not clash with the burgundy walls.
It turns out that you can fix some of that in color correct. But not all of it.
(Color correct is a video post process where you can change the red/green/blue highlights/midtones/shadows in entire frames or in parts of frames. The software is amazingly sophisticated. Using dynamically generated mattes, you can brighten just someone's hair, or cool off just the highlights in someone's hair, or dim everything that's blue.)
When we chose our location, it came painted in bright Tuscan yellow and burgundy. Our first impulse was to paint it. Then we figured out some clever ways we could cover up the walls with boxes and things and the yellow wouldn't pop so much. It was one of those cases where our first instincts were correct. A lot of the yellow walls ended up not getting covered up, and there are frames with huge yellow in them.
We could have repainted, but it seemed like quite a chore to do it ourselves, and expensive to hire painters. In retrospect, we probably should have painted.
So moral of the story: if see something, say something. If, as a director, you see something you're not sure about, then it's probably not what you want, and you should insist on getting it changed. The "not sure" part is you not wanting to be a pain in the ass. But it is your job to ask for what you want (in a respectful way). Sometimes it may be too expensive to get what you want, but seriously consider pushing for it; it's possible as a director to be too nice a guy (or gal).