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?
yes i do trust ico rating sites but it doesnt mean that the ratings are directly proportional to sales because there are lots of projects that are sold out without the perfect ico ratings. though it is a big help for the investors, the inside the team news is more accurate.
Infact the stars or ratings itself exist just for marketing purpose, the developer or the owner of the website rarely give attention into potential project that won't pay them, instead they are trying the value of their ratings just solely for marketing purpose and realizing that most of that kind of website does the same thing, there's no need to put your trust into such sites.