I'll tell you the same that I wrote before 2 days to Quicksolve about trackers list and "open" signups.
For the trackers with open signups I want to say that the best idea is to mark as open ONLY the trackers that they have always their doors open.
For example GFXNews has open signup 1 day per month. Others trackers have permanently their signup open some days of the month or a year.
I believe the best way to see all the trackers with open signups is the "Open Trackers" here: http://torrentinvites.org/f37/ and not the trackers list.
In the trackers list is good to see if the invite system is open (invite only) or closed.