To be quite honest, I typically don't read all the comments to others artwork unless asked to.
There just isn't enough time.

dhama is correct, Artists have the option to request critique or not. Personally when I have critiques for a piece of work, I send it by IM, and I'm very careful and constructive with my comments.
I understand there are those that are unaware of certain courtesies when commenting on others work. However if these comments become derogatory and unproductive, they can be dealt with by staff members. There is a really great bunch of people here and a good set of guidelines concerning these matters. If and when we are made aware of questionable behavior, it's reviewed and dealt with by staff.

When these occur, any member is more than welcome to contact a staff member with their concern.

As far as the point system goes, it can be interpreted in different ways. Some people may not understand that 1 is low and 5 is high. They may have it reversed. Some don't post ratings with their comments. If you want Ratings, this is the chance you take. Many Artists post with no Ratings requested. Myself, I allow ratings, though I pay more attention to the personal comments.

Finally, if there are any comments you see that seem rude and destructive, ("Trolling") please let someone from staff know and it will be handled.

ICM

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Ockham's razor- It's that simple