Am I correct in saying that most stochastic vol models are meant to behave in a way that as atm vol goes up the smile comes down and risk reversals become "less stretched?" - by that i mean say if a 25d RR is trading at 5% for puts when vol is 15%, it would come down from 5% when atm vol goes up to say 20% and go up when atm vol goes down to 10%?
If above is true then why do people keep looking at put vol vs atm ratio in order to initiate some trades at times?
./M