In the real world, college is a time of major transition and change. On television shows where the central characters go to college, the transition theme is also common... and the results aren't always pretty. In fact, there are many once-great teen dramas that went to college and became awful.
It's tricky business to insert the college dynamic into a television show that previously focused on high school, and it must be done with great finesse. Not only are there new people, settings, and situations to contend with, but the core of the show – the characters, the depth and humor, the overall storytelling arc of the series – must remain true to its original spirit. Some shows were able to do this successfully, but the worst series set in college crashed and burned.
More than a few great TV shows that got bad in college didn't survive the change and were canceled. But they make for morbidly fascinating viewing nonetheless. These TV shows that fell victim to the college years often tried to shoehorn their characters into new settings and circumstances, and it just didn't work.