incrediBILL - 9:46 pm on Oct 7, 2012 (gmt 0)

They disappear in underlined links, what does this mean?

That underlines overlap underlined links, people can't tell there's a character there.

Here's an example of what we mean:
[underlines_in_underlined_url.example.com...]

Are the above words separated by spaces or with underlines between the words?

How can you easily tell as the whole thing in underlined?

It's user unfriendly.

Here's an example hyphens instead:
[hyphens-in-underlined-url.example.com...]

When hyphenated and underlined you can still tell it's hyphenated.