Ok I read all this stuff about the pipe cleaner test and how for some it doesn't really matter while for others it can make or break a purchase. I just tried it on my pipes and ALL of them can't pass, even my grandpas bulldog!! I tried twisting and bending and even forcing them. They pass the stem and into the shank but don't go into the pipe. sooo...

How important is the cleaner test for a good smoke and if it's important, what can I do to fix the ones that can't pass?

I do have a few that will not pass the test. Yet they smoke great. My best smokers all pass the test. But that may be my technique.

When a cleaner will not pass with a twist. Or you have to remove the stem, ofttimes that will be a pipe that gurgles. There may be a sharp bend, edge, something changing the flow of air and moisture may buildup at that point. That may, or may not be a problem for everyone.

My Ben Wades were very guilty of this. The hole in the stems were not matching up with that in the shank. On one, the airway was nearly blocked. Wonderful shapes, but not very good smokers until I had Kirk Bosi look at a couple of them. Any reputable pipe repairman should be able to fix any that are a problem.

I would think that a lot has to do with the shape of the pipe. An Oompaul is very difficult IMHO to pass the test along with "some" pipes that have an angled shank. If it is a straight pipe then something is wrong IMHO if it doesn't pass the test. The better the airflow and line up between the stem and bowl makes for a better smoke.

I tend to favor round bent pipes, which is the shape of my pipes.

With that in mind what should I do and who would be well recommended?
?

If you've been smoking them a lot, the airways may be caked a little. If that's the case, they should be cleaned. Soak a pipe cleaner in pipe sweetener, 80 proof bourbon, Everclear, or 90% isporsyl alcohol and shove it in the stem the best you can. Let it soak for 30 minutes, pull it out and pass a bristle pipe cleaner through to remove the loosened cake.

Could be the brand of pipe cleaner. BJ Long's work better for me than Dill's because BJ's are slightly thinner and seem to have slightly stronger spring steel. I can't pass a Dill through an assembled bent like I can a BJ.

Passing a cleaner through a gurgling bent while smoking is the biggest bitch because they jam up and you don't want to disconnect the stem on a hot pipe. I have not tried them but Falcon pipe cleaners may be the answer. They are thinner then the standard variety. 4 Noggins sells them.

Very, I will seldom buy a pipe that is not properly engineered.

the pipe cleaner test is more about pasing a pipe cleaner past the tenon and mortise from stem into shank than any thing elce. This is to make shure that the holes line up so that there is no air turbulance. When u get down to the end were the bowl and shank meet the carbon cake narows the air hole and makes it dam near impisible to get the pipe cleaner to pass. they make what are caled shank reamers wich ream the shank and remove any carbon cake inside the shank that causes narowing of the air way. I just take someting that is long and thin and about the size of the air whole and punch out the carbon cake. that is for strate pipes at least.

There are other engineering factors I look at before the pipe cleaner test.

Bottom dead center for the smoke hole, proper fit of stem to bowl, proper drilling of tobacco chamber.

IIRC Greg Pease had a long post on ASP (years ago) about essential engineering.