They seem biased to me. A friend of mine who's doing an ICO told me that they paid 10ETH for 5 quality ratings and that's that! I noticed that some ICOs with good project, team, and good social media presence are struggling with getting good reviews.
With all that said, should it still be a factor to look at when investing in ICO?
When investing in ICO, you need to take into account as many factors as possible, because only in this way you can form the most objective opinion. Besides, nobody prevents us to engage in a discussion with the experts who assign grades at ICO Rating sites to clarify the reasons for placing a high or low rating.