What are you going to do? Audit the DM's notes and monster stats? You're on the other side of the screen, and you have no idea what's going on on the DM's side. That's why the DM is the dungeon master, and you only pick someone you trust to run a good game, and whose rulings you're willing to follow. The players do not share dungeon master responsibilities and do not help adjudicate the game.
I' don't know, how about start by asking the prospective DM if he shares my sensibilities? If we're a match, great! Sit down and start playing.
If it turns out he lied, then when I catch him I'll need to decide if I want to continue gaming anyway or start looking for a DM that shares my sensibilities. After all, trust has been eroded by his lie.