Referendum for Iran's Political Future

This idea has been in the news for a couple of days now.

Khatami calls for referendum on Iranian government

Of course, Khatami's idea is to have the masses vote on the legitimacy of the results of the recent election and, if it is the will of the people to reject the supposed results, then hold new elections. However, there is no reason why "the people" couldn't spoil each and every one of the ballots by simply writing on them some short carefully chosen slogan that clearly implies a top to bottom rejection of the entire theocratic regime. How could any of the clerics then think their role in politics has the support of "the people"? The old farts should go back to the mosques and attend to "the people's" souls and let the people create a new constitution.

Not that that's going to happen, of course. Khamenei holds the decision making power and such a move would require his consent and he is obviously knows what the result would be.