GE 2004 special

interesting informative article here from aliran by charles hector.

an excerpt here on voting agent:
It is important to ensure that there are no markings. If there is so much as
a black dot or a marking in one of the columns, it can be very dangerous and
you should object to it. Say there is a mark on the row containing the name
of the BN candidate, and when a voter gets the ballot paper and marks for
the DAP candidate: when it comes to the counting process, this ballot paper
will be rejected. But if the voter marked for the BN, then it would be
accepted. Ballots with markings on both rows that contain the names of
different candidates will be considered spoilt votes.

i wonder, what if the voter, on polling day itself, when given the ballot paper to mark the crucial X, spy some markings or teeny weeny dot, can the voter protest? does this means voters are also advised to check and scrutinise the ballot paper?