This client received a notice from Google that the site had been hacked. Sites hosted on GoDaddy seem to be experiencing a lot of this lately. They came to me to get the exploits removed from the site, so that it would stop hurting their SEO rankings.
I rebuilt the entire site locally, making sure that there were no remnants of spammy ads left in the install, and then performed a WordPress Site Migration to another host, so that the insecurity of GoDaddy would not continue to plague this site.
After migrating the site to the new, more secure host, I also installed and set up proper security on the site, to lower the chances of a hacking like this happening again. Since moving to the new host, the client has experienced no problems.