[Gedrin]

When an ME botches a roll, bad things can happen. Cars explode when hit from the rear, airplanes fall from the sky, can openers break suddenly sending sharp bits through the kitchen. Other people can pay, sometimes dearly, for an ME's bad day. We have entire industries of quallity assurance people working to find the botches of ME's.
When an ME botches a roll, he can loose his job, and maybe his entire livelyhood. Usually, it results in a test going bad in an obvious or spectacular way, but it can be really bad.

When a Mage botches a roll, all of the above can happen. Additionally, the maiming usually begins with the Mage, and probably comes with a variety of suffering and debasement only concievable by the demonic forces inadvertently unleashed.