The best way to look at constructive critiscism is to see how it's true, not false. Combat the things that have been highlighted before arguing, and then say what about now... Don't take things personally - after all, people that would give you advice would represent the average surfer, and are more likely to pick up on the little things that count, and would ultimatly provide you with more business. While this may hurt, they probably are right but you feel you have done a good job and are proud, not wanting to radically change your creation. Iv'e been there, we all have...
Agreed, sometimes comments might be harsh, but in the end, don't take them to heart.
Regards
Chris