Related Black hat seo

I am hosting two of my domain on single hostgator account. One of them is making money with adsense and other one with affiliates.
Now the question is that I want to do some black hat seo for the 2nd domain(affiliates one) for traffic gain. However, afraid that it will affect other domain ranking or adsense account.

So just want to know from expert guys will that affect ranking/adsense account or Google will take them on different accounts.

Nobody knows what google does or doesn't do.

If you are scared about it open another hosting account and play with it

No. I did it and nothing happened.

Just because one site uses blackhat techniques to rank and gets penalized, doesn't mean the other 2500 sites on the same server should get penalized too.