Whether you realize it or not, you probably know that to open a jar, you twist the lid to the left, counterclockwise, and that to tighten it, you turn it to the right, clockwise. This seems like an arbitrarily chosen convention—that is, I think the world would have gotten along just as well if jar lids loosened by twisting them clockwise instead of counterclockwise. I may be wrong. However, now that this convention has been established, it should be followed, for the simple reason that it exists. I’m no fan of blind conformity, but making your jars so that they conform to this widespread convention will make it much more likely that the users of your jars will be able to open them easily, without thinking. You’re not going to win any points for creativity from your users if you stray from this convention. In matters like this, it pays to be conventional.
Like jars, the Internet has its own set of conventions. For example, links are traditionally displayed as blue underlined text. Links that have been visited have traditionally been displayed as purple underlined text. If you want your links to look unmistakably link-like, then you should stick to these traditional appearances. However, now that enough people have strayed from these appearances, your link will probably be understood to be a link as long as its text is a different color from the rest of your text. But it’s still true that the more you stray from what’s conventional, the more likely it is that you will be misunderstood.
Because this was the original:
I like potatoes.
this will understood to be a link:
I like potatoes.
more quickly than this will:
I like potatoes.
because it (the first one) changes only the color, while the second appearance changes both the color and the underline.
I don’t think I would go so far as to say that all links everywhere should be blue and underlined, but I would caution against giving words a different color and/or an underline if they are not a link.