not sure if this is in the right place...
Note: this is not only client side as the player i was dueling saw it also
(sorry for no ss but i can't get past the "authenticating" part of login =(
I was at brewfest and got "Completely smashed" and decided to duel someone.
He appeared to me as level 68 , when we finished dueling i Shift+clicked his name to see his guild and it said he was 70. I asked him what level he was and he said 70 and told him what happened and he said it had happened to him also. When the effects of being "completly smashed" wore off I saw him again and his level was 70.
Maybe it could be used for making the enemy in pvp see your level lower than it is.