Hacked Site

Hi, One of my sites has been hacked and I’m finding it difficult to remove. A user of the site got in touch to say the site was advertising viagra – when viewed the site shows no evidence of this. I checked all source code to try and fine any malicious code to no avail, though when I checked the database I found some reference. Has anyone else seen this? I’ve got a back-up though the client has had a lot of content added since. I can’t see any additional files that have been added – could it be a plugin, i have a few installed. Here’s a list:

Advanced Recent Posts Widget
Select All-in-One Event Calendar by Timely
All-in-One Event Calendar by Timely
Animated Back To Top Button
BackUpWordPress
Select Better Search
Better Search
Breadcrumb Trail
Easy Contact Forms
Cookillian
Exec-PHP
Google Analytics for WordPress
Select Hide Widget Title
Hide Widget Title
Hierarchical Pages
Select Image Widget
Image Widget
jQuery Collapse-O-Matic
pageMash
Raw HTML
Really Simple Gallery Widget
Redirection
Sub Pages widget
Video Embed & Thumbnail Generator
WP-Filebase
WP-Table Reloaded

I’m also running better wp security and have run the site through http://sucuri.net/ with no issues found. Any ideas?

Thanks.
Darren Wilson