In my opinion, it is in the intrest of "free" websites (ie Nasdaq) to hold unreliable data so that they can cooperate with research firms who they charge for real accurate data, so that then you, the trader, really have to shell out a couple of dozen 1000s of $$$ to get this data from those research firms and data providers. Barriers of entry are good for larger funds, why would they want Joe Retail to be fully informed?
I use the following resources for comparison to each other knowing they aren't going to be on the same page. Yet, I'll try to make the best informed decision knowing the data vendors I'm using will have some inaccuracies once in awhile. http://www.morningstar.com/ http://seekingalpha.com/ http://www.sec.gov/ http://www.valueline.com/