Hi friends,
If you are freelancer/web designer then it is essential to you that we need to keep our WordPress website up to date. If you are update your website, then hackers are inserting black hat, virus codes into website header (wp-header), it will generate infinity bad links, weak links, broken links with bad words. That will decrease your website progress, defame your brand and increase weak back links.
I have observed it in our recent client's website, which is not updated since long back. We have removed entire site and designed new one.
Using a free theme also causes to such kind of problems, please try to avoid free themes and go for premium themes, any how we need to invest some amount to create, maintain and manage a website.