How do Google penalize subdomains ?

How do Google penalize subdomains ?

If I got domain xxxxxx.com
and under that domain I got subdomain ddd.xxxxxx.com which is penalized
and I got sss.xxxxxx.com which is brand new, does the penalty for ddd.xxxxxx.com or xxxxxx.com(main domain) cover new domain (sss.xxxxxx.com)
or subdomains counts as totally separate ?

Short answer is no, new subdomain won't be penalized at first place

long answer, You can create more new subdomain and it won't be penalized but Google can see overall of site score, If you have more weight of junk subdomain. The whole of domain will be penalized in the end.

I dude. Especially for free subdomains, such blogspot.com ie.