You've heard it here first! Changing a spell from its actual description is being a Jerk DM.So your talking about Jerk DM's. The ones that in the middle of the game make fireballs damage 1d2, just to personalty attack the player of a fire sorcerer character.
How is what and why so different? And players try to discover the secret rules all the time, it's part of the fun.
Now where have i heard a story of a dm who changed a healing spell to its inflict equivalent? or has made summoning create orcus?