Batboard

i use my radio to monitor some channels that have pl but not all units broadcast pl.

if i set to csq i should be able to pick them all up correct?

yes, if set to carrier squelch anytime a carrier is on frequency strong enough to break squelch you will hear it.

I wonder if you're listening through a repeater or to the units directly.

Sometimes a unit will use "talk around" which is slang for operating on the output frequency of the repeater. It is done when two units are in the vicinity of one another and they don't want to clutter up the repeater or be heard by everyone else on that system.

If they are initially heard on the repeater and then go talkaround, you no longer will hear them. That's a function of signal strength, not PL tones or lack thereof.