My house rules say that spells are merely supressed - UNLESS the caster is of higher level than the enchanter, in which case there is a chance for the magic to be permanently dispelled. For example, if an item was crafted by a 12th Level wizard, and then a 15th Level sorcerer cast a Dispel Magic on it, the sorcerer would have to roll 11+ on 1d20 with a +3 modifier for the attempt to succeed. If they are of a lower level than the wizard, it simply fails. This supports the spirit of the rules, while giving both the wizard and the sorcerer a chance for success in the conflict.