A reliable source of comments on Machine Learning papers?

I'm sure we all faced the challenge of going thought the same classic (and not so classic) papers on Machine Learning and read them, fail to understand them because there are some bits of information missing: comments. Some papers are difficult to understand (maybe the explanation is not exactly clear), some can have small (or even big!) mistakes, some can have missing information to understand them. My question is: is there any reliable collaborative source of comments on Machine Learning papers (even maybe with comments per sentence or formula). It can be a blog, a wiki or a subreddit.