Welcome to WebmasterWorld Guest from 188.8.131.52
[edited by: goodroi at 10:46 am (utc) on Jan 8, 2013]
[edit reason] Please no specifics [/edit]
Unfortunately, you cannot prevent others from building links to your site, even from a bad site.
All you can do is try to deal with it afterwardsWell just found that google has announced disavaw tool in the GWT in oct-nov 2012. It can be a handy tool if in the future the site gets in trouble due to bad links that would be posted by your competitor