Given the choice, it would have no lines and side dots where the frets would have been. But, it's not a perfect world, so I have a de-fretted Thunderbird with walnut strips where the frets used to be and dots where they shouldn't be on a fretless. That means the markings are where you don't want them and you can't see the lines very well at all. Why do things the easy way? I'm used to it now, but doing it over again, I would remove the dots entirely, put the walnut strips in for the frets, and then install dots at the appropriate places. As it is, it looks a little weird, but it works just fine. There's always some guy (always a guy) in the audience who figures out that a fretless Thunderbird is an oddity and wants to know about it. His girlfriend (assuming he has one) is always unimpressed.
I can't see the fretboard/fingerboard while playing anyway.