This very question has been discussed many, many times; do a search and i'm sure you'll find what you're looking for. For the most part, it seems that people think that Cooley's negative reputation has a lot to do with the fact that they have created their own ranking system (in which, of course, they are rather highly ranked). This ranking system has some questionable categories, including square footage of library. In an obvious attempt to simply "boost" their numbers, they include such distinctions. All of this compounds to Cooley receiving negative publicity. Other T4's do not try to game their own rankings, and as such, they don't receive as much negative publicity.