they have the same info about each other if they chose to do the due diligence. if a player asks me to play for money i have no obligation to tell him i am better. or even if i am and ask for a spot. its gambling. you try to get the best of your opponent without cheating.
what is cheating is in each owns mind. especially from the ones that lose all the time.
if a chess master is in the park where they are gambling and asks someone to play and they say how good are you. he says not that good. whats wrong about that. they guy that asked didnt volunteer his rating.
if you are not a gambler dont gamble. and if you do expect to lose. and blame yourself for being stupid, if you gamble with a stranger you take your chances.