The milling procedure can be really considered a fast and clean way to realize pc prototypes.
In the picture there is a normal double face pcb realized using such a procedure. In any case the milling procedure is not free from errors or imperfections that may affect the final result.
A well milled pcb must present a clean groove and a clean track without any indecision. As you can see in this picture
all furrows and all tracks are very well delimited assuring, in this case, a clean 'transport' of the signals and of the currents involved in the circuitery.
A pcb created with the milling procedure, however, must be controlled very well before to solder the components because there are some common mistakes that may affect seriously the result.
In 
the pictures there are a couple of very common errors examples. In the first picture it is shown a problem, where the copper it is not really cut by the cnc machine but it is simply pushed into the groove. On the second picture the problem resides where the track is not completely finished. very probably due to the proximity between the tracks.
Unfortunately these mistakes are quite common but they can be solved simply looking at the pcb carefully and can be immediately corrected by a cutter using a magnifying glass.
