You can't believe those crafty Persian wizards.
Oh sure, they'll charge you up the wazoo for the privilege of having an invisibility spell cast upon you, but then you walk into a bank, start snatching money out of peoples' hands, and they beat the crap out of you, because, it turns out, they can all see you.
Ever consider looking in a mirror first?
The man told the court, 'I made a mistake. I understand now what a big trick was played on me.'
Silly criminal - cloaks make you invisible, not spells. Everyone knows that.