Most muppets who fit them will fail the MOT as the aim is not set correctly or they are using cheap and nasty LED that cannot be aimed properly. Set correctly they are fine.
The issue isn't just cheap bulbs but the wrong bulbs. They're are 2 types, projector and reflector, most sold on fleebay etc are for the former, fine if you bike is fitted with projector head lights, they won't work on reflector head lights, such as FZS/600/1000. The same applies to LED, most quality units can be adjusted, cheap knock offs either can't or the chip is positioned incorrectly and no amount of adjustment will work.