1. "We all think that ..."

This phrase is all wrong because at first you can not speak on behalf of others and secondly you can not allude that everyone thinks the same way you. When this sentence is said it inadvertently causes some kind of pressure on the other person making him feel "excluded" or simply because he is giving wrong suggestions on behalf of everyone. 

2. "Do you have a minute?"

It seems like a polite question, but from the way it is said it is certain that it "forces" the other person to say YES. At the end of the day you are not interested in whether or not your colleague has time, you are just waiting for their approval to proceed with the request in question. It would be fairer to avoid pauses and get straight to the point.

3. "I'm not saying you should do it, but ..."

This is like saying, "Say something to someone as if you did not say it." The brain does not process the word "I'm not saying that .." and takes for granted only "you have to do it", said in a less commanding form. Another manipulative sentence, which you misunderstand quite simply.

4. "Do not spend all night dealing with this."

It seems like you are just taking care of your colleague's well-being, but it is actually a pure requirement to get the job done on time. It's like saying, "I love you tomorrow morning at all costs." It would be best to be clear about delivery deadlines and so on. 

5. "Don't you think so?"

Such phrases do not invite you to the discussion, but inadvertently seek to get one more approval. When bosses say that, they want to put you in an awkward position if you do not agree with their idea / opinion. Better would be a question like, "From your perspective, what do you think?"

Source: Huffington Post