The only hacked sites I had to fix were running on ... [prepare your stomach] ... Joomla.
I'm not sure if there is even one single solid developer for Joomla. This shit piece has more vulnerabilities than a crack hobo infested with pest-ebola-hyperAIDS.

The sites were full of hidden viagra and pr0n ads and links so the crawlers would list them.

Luckily for me, I was able to pursuade the clients in all 3 cases to build a new site from scratch on a different CMS.