Diverse ref domains make the site gain more trust?

Hello,

Some people in whitehat SEO said that blog comments are still very fine in case the ref domains are related (you can find the famous T0mmy's post) . But how about other authority domain like *.edu, *.gov (like .mit.edu, .berkeley.edu..) ? Do they make your site gain more trust or just a group of junk links?
(Links are placed as signature or something like that when you create an account in these authority site)

And how about other authority sites which are not related with your niche?

Thanks

All links are good if they are from not spammed sites. Where you put comment on valuable site and link to your side it is still very good (site don't need to be related to yours)

Hi ekapek,

Thanks for your reply.
Are blog comments equal to links from account profiles?
I see a lot of services out there which do create account profiles with a link inside.
These accounts from big sites like .mit.edu, .berkeley.edu.. Are these still good?

Thanks

I think that they can be better on moderated sites, where you have to put it mannualy related to blog post and author have to accept it. Such sites don't have thousands of external links.