Why do conservatives reference "think tanks" in their arguments?

I've always been fascinated by the whole alternative universe of conservative think tanks, like the Fraser Institute or the American Enterprise Institute, or literally hundreds of others. I've found that when a conservative will try to actually use "facts" in their arguments, they'll say, "Hey, it says so at the Fraser Institute", not understanding that it's a conservative organization with a partisan view point. I'm amazed that even educated conservatives don't really seem to get this. Liberals like to use peer reviewed, objective sources to make their case, because it's based on a thing called science, but these conservatives literally can't make these distinctions. What's up with that?