The neighbor did this to us last year right when it got really hot and dry.  The damage went halfway across a square 160.  The worst damaged beans were 5-10 bushel less, but the ones in the middle of the field were actually better, so I don't think we really lost too much out of the whole deal.  It makes you mad though when the neighbor sprays dicamba on a hot windy day when the wind is blowing toward your beans.