In Eclipse there is a plugin named checkstyle. It is to check whether your code is as per the coding standards. For severe errors it shows yellow mark on error position indicator. And as the severity decreases the darkness of yellow mark also decreases. At some point of time it becomes so faint that you can even miss it. We can ignore them actually as they are not that severe.

One use of such decrease in visibility that I realized –
If you have less time to checkstyle your code, you can put your spectacles aside and start applying checkstyle. :D
Yeah, this is useful only for those who have spectacles. :P