I see this is an old, resurrected thread, but I'll add a bit of advice anyway.
A friend smoked the end of a cigar in one of my cobs and I almost never got the smell out. I don't mind ghosting, and don't bother devoting different pipes to different blends. I never even notice the ghosting, unless it's some huge difference like smoknig a bowl of Nightcap and then smoking a bowl of Lane 1Q in the same pipe immediately afterward.
Anyway, though I'm not usually finicky about ghosting, the cigar ghost was brutal. The same guy also did it in his own pipe, and after a while he complained that what he didn't like about pipe smoking was that you tasted the pipe more than the tobacco. I told him that shouldn't be the case, and offered to clean his pipe. I deep cleaned it, and it took a heck of a lot of cleaning to get that ghost out: reaming bowl down to briar, alcohol/cotton ball treatments, alcohol baths for stem, then more cleaning with rum, etc.