@siege @SteveMino sorry for randomly responding to this three days later. I used to be an electoral administrator. By law any ballot paper marked with anything other than a tick or a cross clearly in a box is considered doubtful. These are pulled out and reviewed individually by staff.

Candidates and agents at the count get called over to view every decision as to who the vote is for, if it's spoilt, or if it's unclear and therefore considered spoilt. It's a major part of the count