why is it bad to link to gambling sites?

I've heard you shouldn't do this, but why? And isn't someone linking to them because if not how are they placing?

It's not like its bad to link to a gambling site. There are so many reasons why should not link to a gambling site unless you own a site/blog that talks about gambling.

First of all, The gambling niche is similar to "payday loans" or "viagra" niche with extreme competition both in terms of SEO and PPC. So your site will easily get into Google's radar and linking to them will get your site manually reviewed. Let's say you own a blog a network and link to a gambling site. Both your network and the sites that you're linking to will be manually reviewed and penalized if a single competitor complains about it.

Because Google has arbitrarily decided that they have moral superiority, and as part of that, they cast judgment on people involved in gambling, and devalue their links accordingly.

Pills, Porn and Gambling.....and Google shakes their head with disgust!