Domain Do-Follow/No-Follow ratios

Are domains with 99% do-follows considered spammy domains or does it not matter? What percentage do you follow? I've seen the biggest sites with 13% no follows, is 5% no follows and above considered safe?

99% do follow does look unnatural not spammy.
The ratio should look natural. It could be be anything 20% to 90-95% do follow depending on your niche and how much spam links are there.
Some site naturally get spam links due to no bot blocker, no firewall, public access to rss feed.
As a thumb rule if you got lot of natural links you can make your own do follow backlinks with random frequency. It will blend into the crowd of the links.

DF / NF ratio used to matter in the past, and I always kept my sites at around 60-70% DF links. But this year I've seen a website (shared here on the forum) with 100% DF links ranking like crazy, and it's not like they had only 1 or 2 links (which is easy for both of them to be DF since they're so few of them), the site had like 1000s of links, all of them DF, so yeah... not sure that I trust this anymore...

my personal rule on this is if it has anything below 50% i will pass on it when choosing my daily back orders