Learn the difference between tight passive and pure passivity.
Understand that against passive players, both their raising and calling ranges will be stronger than a more aggressive player who plays the same range of hands.
Let's take an example, let's say we're against two players who never 3 bet the BB HU, one for strategic / balance reasons and one because he's terrified to raise anything but the nuts (but will always raise the nuts if he has them).
We open EP and they both defend an approx 25% range, something like:
22+, A2s+, K9s+, QTs+, JTs, T9s, 98s, A7o+, A5o, KTo+, QTo+, JTo
The flop is J43r and we c-bet and they both elect to fold the bad hands in their range (98s, T9s, QTo, KTo, all the A6-AT w/ no BDFD, K9 + KT w/ no BDFD).
Check-raise ranges could look like:
Agg: JJ+, 44, 33, AJ, KJ, QJs (w/ BDFD), QTs (w/ BDFD)
Passive: JJ
Check-call ranges could look like:
Agg: 55-TT, 22, QJ (no BDFD), JT, BDFD: (K9s, KTs, ATs, A9s, A8s, A7s, A6s), A5, A4s, A3s, A2s, AK, AQ, KQ
Passive: QQ+, 22-TT, AJ, KJ, QJs (w/ BDFD), QTs (w/ BDFD), QJ (no BDFD), JT, BDFD: (K9s, KTs, ATs, A9s, A8s, A7s, A6s), A5, A4s, A3s, A2s, AK, AQ, KQ
So let's say you cbet 100% of an 11.5% open versus both. Equities versus each group (approximate)
Check raise:
Agg: 24%
Passive: 6.4%
Check call:
Agg: 56.1%
Passive: 48.5%
Now you may be saying "how can a passive player, with the same range as an aggressive player, have stronger ranges in both scenarios? Well, because of frequencies. Let's see how many combos make up each group for each player:
Check raise:
Agg: 58
Passive: 3
Check call:
Agg: 158
Passive: 213
So while both action groups have less equity for the aggressive player, he takes the one w/ more equity far more often than the passive player, so their overall continuing equity converges to the same (with some rounding errors as I may have entered ranges in wrong).
This informs why bluffing these player types is ill-advised: they just have stronger ranges than most when taking passive lines. But when you don't want to be bluffing people, what do you want to do? Answer is value bet with any edge you can find, and give up on your low equity bluffs frequently.
These kind of players can be annoying to play (as you'd much rather see a 60/30 guy than a 25/2 guy), but you'll eventually get their money because when you have a good hand, they call, and when you have a bad hand, they don't get paid.