Lately, I have seen a couple of sites employing the same methodology to rank webhosts.

While I wish to congratulate the person who came up with the novel idea, however, the methodology applied is flawed at so many levels.

I was looking for recommendations for a dedicated server and happened to land on one of these sites. My observation is that if a host ranks 1-5 in say 'shared hosting', it will rank high in all the other hosting environments (dedicated,cloud, VPS) that it offers.

Their ranking is based on twitter "signals". When people applaud or disapprove a given webhost. They won't say
Hey, What an awesome VPS host or The worst cloud host ever

In a constrained environment of 140 characters, all the terms are normally pushed into a generic category webhost

Then there can be so many other issues like people not coming out, or not wanting to criticize a host when they are already hosting a site with them or not enough reviews for that small company which is doing awesome job...

Yeah, may be a reference point but won't solely rely on these rankings.
"Webhosting Ratings" still remains a problem looking to be solved.