I think it's a matter of "taste," as in whatever yours (or the circle you hang with) tastes are. Generally conflicting colors and silhouettes and such do the same thing where your eyes dart from place to place in search of some harmony, but depending on if that is the intention of your outfit (to be "out there" vs subtle) it's not taboo, per se. But that's just my view as a rather new to luxury, former emo that wears corsets and thigh highs to my creative work environment, feels. I personally do not wear things with major logos, however I do note when others wear them and when I see a lot of logos all at once, I do get the "walking billboard" vibe. To me, cohesive color and vibe matters more.