What I've observed over the few months that I've been a member here is that most of the people who participate in contests do it simply because they enjoy Competitive Programming; most of us aren't here to just inflate our ratings.
What if we we could put a system in place that is based on 'trusted members' (like trusted participants, but a bit more strict) volunteering to personally inspect a few randomly assigned anonymous submissions and check and flag submissions for things such as code obfuscation which are easily able to get through today's Plagiarism Detection System.

Because there are tens of thousands of active members who would satisfy the above criteria, every member would have to scrutinize at most a couple of accepted solutions and so this system should be easy to scale. Because the entries would be anonymous and people would have no way of knowing which users' submissions they'll have to scrutinize next, the chances of concerted mob behavior to 'game' the system would also be very, very low...
What to do with the submissions which have been flagged a certain number of times on a few different parameters is bound to remain an open question for at least a while and it would be great if you could share your suggestions...

Edit:
For scrutinizing submissions, a new section could be added on the official website (like contests and problemset) that is accessible to only the trusted members (most of us), and people would be able to flag submissions only from this section. All submissions are public for viewing, but when they are to be checked for plagiarism, on this section, they'll appear as randomly assigned anonymous entries.
Further, the Plag. Detection System could flag suspicious submissions for things such as copious amounts of comments, and only those submissions would appear on this section.