You definitely have to accumulate a few pipes to make trading them in worthwhile, unless you have one or two high-end pipes, which most of us wouldn't want to trade. Even excellent smokers improve over the years, in most cases, so that is another case for not trading. However, when you have enough so that you notice a few that are true wallflowers, even if they aren't especially poor smokers, it may be time to think about turning them into one pipe you will smoke more often. I tend to bond with pipes, as mementos I guess, since they are inanimate.