so the big question to other bloggers

There for a time I had many people commenting on my blog posts, sharing their thoughts too, which is what I want in writing a blog. But then come the people who post just to share their websites, like a million casino posts, or designer handbags or any plethora of commenters. So I turn off the comment button and I now have to sort through hundreds of posts to see if there is a legitimate post to publish. How do you other  bloggers deal with this? It is incredibly frustrating and a huge waste of time, I gave up for quite a while, but I don't want to not be able to have you sincere bloggers be able to post here..

Any help would be great appreciated!