The politics of each college tend to shift around from year to year, depending on who is making waves, the JCR elections, etc, etc. The reputations tend to be based on certain 'celebrated' years or the results of active PR by some activist or other at particular points. The academics in colleges represent a longer term politics, but there is no particular reason why as a student you have to get in line with that. So basically, you can ignore the stereotypes, they are at best a vague description and often just irrelevant.