My highlighting scheme is to very slightly dim comments, because they tend to be more dense than code. For example: http://imgur.com/a/bxfBO

I think that this is dependent on what you are trying to do. If you want to understand what a program does than this is the way to go. If you want to program than you don't necessarily need the comments to be that visible.

I'm arguing that dimming them makes them easier to see. Code and comments are interspersed, and are each harder to see when they're the same color.