That's very poor fudging form. If you describe the boss as being no tougher than a regular goblin, you should run it as such. Changing the stats then is like trying to fudge a die that you rolled in the open.
However, in my experience, it's very seldom that the PCs have such detailed information about their opposition.
Yeah, Lost Soul & S'Mon have change the parameters by declaring that the GM gave clues as to the strength level of the monster.
I don't assume that opportunity came up when I cited it. As such, the players don't know the BBEG is more different than could be expected.
Which could be pretty common when DMs customize and level monsters (Hey, the boss is just an orc, 1HD! Wrong!!!)
As to the definition of "fair" I did put that in quotes for a reason. If the party undertakes the "Quest of Level Appropriateness" as opposed to the Dungeon of TPK Monsters, then they have self selected the EL/CR they expect to fight. Changing the BBEG to be TPK-level would not be fair, especially if there are no clues the the BBEG is at TPK level of strength.
My point is, changing stuff on the fly isn't much different than choosing crappy numbers during the design stage. As such, Since it is acceptable to design badly, it must therefore be acceptable to impromptu change things.
Hopefully in fact, the reason for a FUDGE is to CORRECT a bad design choice.
One thing I always challenge in these threads is the notion that there is a pure competition and accomplishment if your GM never fudges. Your PC suceeds, ultimately because the DM interpretted your choices to let you and because he did not put impossible barriers in front of your PC. Any sense of accomplishment you get is by his cooperation. If the GM did a bad design job, you will not win. If the GM did a bad execution job, you will not win. There is more behind your victory at the game table than your choices as a player.
As such, some GMs seem to use Fudging as a correction in order to cooperate with the player's intent.
