I have perception at 4 and apprenance at 8, the Lizardman have a 70% chance of appearing each time you change rooms or interact with anything that the eye icon reveals, you might also randomly have the hide and attack him choices if he did not see you each time he appears, the hide option can allow you to avoid him, if you have a save on the screen before the stairs leading to floor 2, the door on the right can allow you to reset your lust back to 0, you can use that to farm levels, there is another restroom after using the stairs that leads to floor 3 that you can use as well, otherwise you might have to load the save before entering the dungeon if you don't want to save scum through it.