There should be measures put in place preventing lawmakers from sneaking in questionable (or any) legislation. It is a wanton subversion of democracy to employ underhanded methods to pass unpopular laws.
An unpopular law would be something like cutting Social Security benefits. That's something people would actually care about.
And CISPA is not unpopular, at least not generally. Most voters have no idea what it is, nor would they care if you explained it to them. What you really have is one small bloc: Google, Facebook, government security people, etc, supporting CISPA, and one small bloc, the ACLU, EFF, etc, opposing it. If CISPA gets passed, it's not some sneaky thing getting passed in an underhanded way against the wishes of the majority of the people. It's one small bloc winning out over another small bloc over an issue the majority of people don't care about.
(The problem with having representatives just being direct, non-autonomous proxies of their constituents is that people will vote for things that benefit them and then not vote to pay for it..)