This question already has an answer here:
Occassionally, my posts get down-voted. However, most of the time they are up-voted.
When I get a positive reputation change, you get a notification at the top of the site that says
+whatever reputation for things like up-votes, accepts and edits. However, when you lose reputation, you have to notice your reputation go down strangely and then actively look in your reputation history to see where the down-vote came from.
So my question is, bearing in mind that there are notifications for positive changes in green; surely it would be logical to notify negative reputation changes in red for example?