Should the actual liquid in the shot be cloudy or clear

be cloudy or clear?? I am a nurse--and sometimes the injection is cloudy and some times its clear. As a nurse--generally if the fluid is cloudy the is precipitate in it and it can't be used--I asked my doctor about it after my last shot and he said it was different manufacturers and the dosage--I don't believe him--and do not regularly have opportunity to give it and know what its to look like cuz i am a labor and delivery RN---