I found a wired issue on sitepoint signature, some of which are no-follow, but some are do-follow, who can explain it? 
I believe the previous rule was you needed x number of posts to get a do follow sig.
It really doesn’t matter anymore as signatures are no longer displayed to search engine spiders either way.
are you sure???
Positive.
Does it discourage garbage, fluff posters with billboard signatures who are wasting their time if they think they are going to get backlinks from posting meaningless posts all over the forums…?
Guess not 
Whatever the boss (spikeZ) says… furthermore… simply look at my signature where it says “your singnature is not visible to search engines” 
log out from the forums and see for yourself
Oh, I checked when i logouted, all of the signatures were gone!
It is true?
yep, it’s true
search engines cannot see your signature links
please tell all your seo backlinking friends