My assessment of the aforementioned stereotypes:
hippy/pot-head: You will certainly see hippy-like appearance and hippy-like behavior from a small number of students just about everyday; pot has a much smaller presence here than I expected; cigarettes, however, has a bigger presence than I imagined; other drugs can be found without too much effort (if one so desires). On the other hand, if you are annoyed by all things drug related, you can effortlessly turn a blind eye and pretend it doesn't exist (by 'it', I mean the harder drugs aside from marijuana).
Liberal arts "bubble world": LC's geographical location certainly feeds that stereotype. It is situated in a quiet and peaceful forest like environment, in a wealthy part of southern Portland. If awesome natural scenery fits well with your study style, this is a serious plus. LC has, for the most part, a beautiful campus, especially during the summer.
Wealth of the student body: There are no shortage of well-to-do upper-middle class students attending LC, but there are also plenty of lower income students as well. A large majority of the student body receives some kind of need-based financial aid from one source or another. Like every other student body, you'll find people who work part/full time to (barely) make ends meet. In my opinion, what perpetuates this (largely inaccurate) stereotype of a wealthy student body is the high cost of the school. The total cost for one school year could easily exceed $40,000: $30K tuition, ~$8K room & board, ~$500-$1000 books, ~$1000-2000 misc. fees, supplies, transportation/logistics, entertainment expenditures, etc. This certainly leans towards the high end as far as college education costs are concerned.
Political orientation: Yes, as stereotyped, LC is overwhelmingly liberal. You can find EVERY liberal stereotype here: anti-globalization activists, extreme feminists, tiny grass-roots anti-establishment student organizations/clubs, over-zealous human rights activists, anti-war activists, socialists, idealistic philosophers, NGO volunteers, etc. However, at one point, I heard a professor comment that while there is certainly a strict adherence to the liberal/left wing ideology, it rarely translates into meaningful action. I hardly hear ANY sort of conservative leaning view points expressed on campus. I consider myself liberal leaning (especially on social issues), but sometimes LC leans too far even for my tastes.
LC Academics: There are quite a few students at LC who have been awarded prestigious scholarships and fellowships at LC (i.e. Fulbright & Truman scholars). Plenty of students apply for and receive grants of all types to conduct independent research on a wide array of subjects from biology to international affairs. At the end of every semester, one would often see students who are practically living at the library (which is open practically 24/7), preparing for final projects/papers/exams. In short, there is no lack of academic rigor at LC.