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This is more of a request than a question, but if people down vote questions or answers could you please leave a comment in the appropriate place.
The point of the voting system is so good q/a can be easily spotted and bad q/a can be improved but if you don't tell people why you down voted them how can they improve it ?
Don't get me wrong down voting can be useful for helping manage bad questions but often times it is simply bad spelling or grammar that can simply be edited and then the votes can be changed.
As a guideline an effective procedure for down voting is as follows
First cast your down vote on the appropriate q or a,
Leave a small comment saying why you down voted (ie -1 the spelling is so bad I could not even read this )
Return later to see if the q/a has been edited, if it has, and meets your standards, then you can change your vote (returning any lost rep to you and the OP ) and remove your comment or edit it yourself to earn a little rep and help out the site.
This may seem like a small issue but it is an annoying and common problem I for one would like to see gone, it just seems like a common courtesy to me but I understand new users may simply not know how voting works so I write this to try combat this issue.