Playing against very passive players
My approach in general is to try and be aggressive in most spots no matter the type of opponent, but I do adjust after I'm confident what type of opponent I'm playing against and if it's very passive players (calling stations) - I switch to way more value betting and pretty much no bluffs... also, in your example, because this type of player rarely bluffs on the river (especially if it's a check/raise), I'm also folding most of the time - IMO it's a mistake many players make when playing against passive players * they assume this players are 'never' strong - well, they can wake-up with the nuts from time to time, the good thing is that they usually give you easy signs when this happens and the check/raise is definitely one of them...