I love cobs. They smoke great and allow you to have a "rotation" quickly and cheaply. Actually, my cobs turn out to be not-so-cheap because I get forever stems for them. Even with a forever stem they are far from pricey. Depending on my mood, there are times when I think there is nothing finer than some Carter Hall in a cob. I'm going to have some now. I smoke my cobs without a filter (many, maybe all, of the forever stems don't accept filters), but if you like it with a filter . . . whatever works best for you.
I'm no expert on saliva, but the consensus here seems to be that not much saliva runs down the stem and that the moisture you are collecting in the stem is probably condensation from the burning tobacco: your tobacco is too moist or you are puffing to furiously, or both. I tend to believe this because most of the time I smoke pretty dry, but I have some blends and some pipes that gurgle a bit, so I'm thinking its not me.
Experiment a bit. Let a bit of tobacco dry out before smoking it. Also try slowing down your puffing. Not that I'd know; I tend to puff like a locomotive. But that's what the others here always say.
Nevertheless, you can't beat a cob, especially for the price. And, if you like the filter, hey, they are pretty inexpensive. Enjoy.