In my experience,borrowing money from a friend or relative can ruin a good relationship. I think that borrowing more than three days worth or salary is essentially a business deal. In these types of situations, I agree with the opinion that borrowing money form a friend can damage the friendship.
First of all,asking a friend for money puts your friend in an uncomfortable position. It is very difficult for a friend to say "no",even if his good business sense tells him to.I think most people will say "yes",just to save face,but may develop a grudge against you for putting them in that uncomfortable position.
Second,I think borrowing money from a friend can alter his perception of you. He might receive you as reckless as or less responsible than he thought.I think most people would prefer to have a careful and responsible friend and you may no longer fit the bill.
Finally,if you borrow money from a friend,it changes the balance in the relationship.You are no longer equal to your friend.Now,you owe him a favor.He might expect you to treat him better or do more things for him in the future.
To be in brief,I think borrowing money from a friend can hurt friendship.It creates more problems than it solves.It is better to borrow money from a bank.