I tested the bot on arena, and 2 times i get 9 wins, 3 or 4 times i got 6-7 wins and 2 or 3 times got 1-2 wins...
In my case the bests wins was with Pala and mage, the rest was with shaman, druid...
Now, i only bot arena if i must stay away from my PC all day and i have Paladin to play. If not, i don't bot in arena, its risky and i like to play Hearthstone xD
Bot just to farm gold, or rank up if you want...