Fenders too large?
 

I just acquired a bicycle, and I plan to add fenders. It currently has 700c x 30mm tires, and I plan to eventually switch to slicks (I figure if we have snow this winter, I'll still have the treaded tires just in case). I've been seeing fenders recommended for certain tire sizes, some of which show both a minimum and maximum tire size to use. Is it possible to have fenders too large for the tire? What is the detriment, besides aesthetics?

Large fenders will not hurt anything and may even provide more protection. The only downside will be aerodynamic drag. Believe me, I know that from experience.

Thanks much. I knew there had to me more to it than just looks.