It’s not a fallacy, it’s an ideal, a goal to be strived for while accepting human limitations. No one can perfectly design and build a house, but we don’t shrug and say “Perfect right angles are an illusion, enjoy your crooked house.” Besides, there are laws around this concerned with something called *the appearance of impropriety” which is to be avoided by judges, elected officials, and others. You can legitimately get yourself in deep muck, not only by being improper, but by merely seeming to be (to a reasonable person standard).