There will be such problems mainly mechanical watches or quartz watches. LCD watch because of its internal structure of the different, usually not because of the magnets failure.
Many mechanical watch movement are made of steel. If the watch is placed near a magnet, the steel movement is magnetized with its own magnetic field. Because the parts inside the watch are very small, a little bit of external force will be disturbed. Therefore, the newly generated magnetic field is very easy to watch the deviation of the internal components of the operation, so that the pointer go wrong.
In addition, there is a quartz watch inside the circle around a lot of coils, the magnet near the inside of the electronic original will be abnormal, affecting the pointer rotation.
Someone has done experiments, generally magnetic appliances, watches away from its 10 cm above, will not be affected by the magnetic field. In case the watch by the magnetic, do not worry too much, you can send to the watch shop, so that maintenance staff to help degaussing, the watch can be restored to normal.