writing like this is correct or not ?

i seen so many people are writing...

click for buy amazon products, buy amazon products click here... something like that.... is it legal to write like this or not ??? can i add this words in my link ????

 

Well, it is legal but has no value.
Think you have a website of Ice-cream and keyword is "Vanilla Icecream" and you target your keyword like this
buy fresh and tasty Vanilla Icecreams click here and link only "click here", so think what is the benefit to doing this.
People usually link these types of words or phrases as you mentioned in your thread but they have no real value, so avoid these types of words.

 

It is Marketing 101, you need a call-to-action.

 

Well this its legal but its unprofesional and you drease your click to rate as people will thing that you only try to sell them

 

If you mislead people, intentional or not, you will lost all credibility with them.

I'm assuming this would not be your intention.