I’ve read too many sentences that contain the words ‘should of’ when speaking of someone who should have been doing something. Now I know it often sounds like that is what people are saying, but it isn’t. What they’re really saying is ‘should have’. And that is what you should be writing when you are talking about something someone should have been doing. To write ‘should of’ just lets people know you are not very educated in the ways of the English language. And if you are a citizen of an English speaking country, then this is not acceptable. If you want to sound intelligent, you need to speak your own language properly. It is an unconscious act that everybody automatically treats anyone with respect when he/she speaks his/her language properly. It happens everywhere. Can be actually witnessed if you pay close enough attention. So take these lessons to heart. Your life can be greatly improved simply by speaking your language properly. Try it.