Do you guys think that black hat seo still works after recent google updates?
Any SEO tactics that move the needle will become blackhat once they go mainstream. So in that sense any SEO tactics that work are black hat. SEO strategies that work is a different story (So calm down you Whitey McWhitehats!)
What about Gordon Greyhats ?
One of my websites is dropping every day and that's the one that I always work on.
while I'm having another website that is moving up in SERP every day, and I do almost nothing to rank it, except a few simple projects.
How often are you working on it ? Do you mean you're doing seo on it all the time ?
Pause your seo stuff for a couple of days, let things settle.
Add some new content ( if you've not done so for a while )
Quality over quantity with seo, but don't go for overkill.
I'm building tiers to it almost every day!
I haven't done any new contents directly to the website for a while now.
But remember that the other website that is ranking well and keeps going up and up like a rocket, is the one that I have had no attention to it for at least a year now!
Do you think that I need to stop the Tier link building for the one that I'm concern about?
Personally yes and give it chance to breathe. Add 1 or 2 new articles, decent length 1000+ words each but leave off page seo for a few days at least.