Leave pornographic materials amongst public documents.
This works best if there is a receiving area for clients and/or guests. Place pornographic materials (photos, magazines) amongst the magazines or flyers that are left as reading materials. This works well at tarnishing the reputation of the company with the public.
If there is no public area to exploit, place pornographic materials amongst documents/resources that are shared between staff members.
The form of pornography you use should be as alarming as possible. Think grannies, BDSM, and other non-mainstream subjects.