[Arizona]

"In my experience (which is admittedly very limited, mainly to cobs) with filtered pipes, all they do is foul up the flavor after a while. It seems like the filter gets old and stale after only a few smokes, so I always just took them out of the cobs."

Precisely...

TOSS IT IN THE TRASH and clean your pipe like you would normally. The filter is worthless and just COLLECTS tars, moisture, etc and fouls up the taste of your smoke as it builds up. A properly maintained pipe has none of these problems...